diff --git a/backend/2of5.c b/backend/2of5.c
index 60010b84..316697c1 100644
--- a/backend/2of5.c
+++ b/backend/2of5.c
@@ -184,7 +184,7 @@ int logic_two_of_five(struct zint_symbol *symbol, unsigned char source[], int le
 /* Code 2 of 5 Interleaved */
 int interleaved_two_of_five(struct zint_symbol *symbol, const unsigned char source[], size_t length) {
 
-    int i, j, k, error_number;
+    int i, j, error_number;
     char bars[7], spaces[7], mixed[14], dest[1000];
 #ifndef _MSC_VER
     unsigned char temp[length + 2];
@@ -222,7 +222,7 @@ int interleaved_two_of_five(struct zint_symbol *symbol, const unsigned char sour
         lookup(NEON, C25InterTable, temp[i + 1], spaces);
 
         /* then merge (interlace) the strings together */
-        k = 0;
+        int k = 0;
         for (j = 0; j <= 4; j++) {
             mixed[k] = bars[j];
             k++;
diff --git a/backend/auspost.c b/backend/auspost.c
index 35438a7c..5f787ffe 100644
--- a/backend/auspost.c
+++ b/backend/auspost.c
@@ -104,7 +104,7 @@ int australia_post(struct zint_symbol *symbol, unsigned char source[], int lengt
        1 = Tracker and Ascender
        2 = Tracker and Descender
        3 = Tracker only */
-    int error_number, zeroes;
+    int error_number;
     int writer;
     unsigned int loopey, reader;
     size_t h;
@@ -160,7 +160,7 @@ int australia_post(struct zint_symbol *symbol, unsigned char source[], int lengt
         }
 
         /* Add leading zeros as required */
-        zeroes = 8 - length;
+        int zeroes = 8 - length;
         memset(localstr, '0', zeroes);
         localstr[8] = '\0';
     }
diff --git a/backend/aztec.c b/backend/aztec.c
index 9b173753..4a8c61cb 100644
--- a/backend/aztec.c
+++ b/backend/aztec.c
@@ -134,14 +134,19 @@ static int aztec_text_process(const unsigned char source[], const size_t src_len
     char *reduced_encode_mode;
     int reduced_length;
     int byte_mode = 0;
-    
-    encode_mode=(char*)alloca(src_len);
-    reduced_source=(char*)alloca(src_len);
-    reduced_encode_mode=(char*)alloca(src_len);
+
+    encode_mode=(char*)malloc(src_len);
+    reduced_source=(char*)malloc(src_len);
+    reduced_encode_mode=(char*)malloc(src_len);
 
     if ((!encode_mode) ||
         (!reduced_source) ||
-        (!reduced_encode_mode)) return -1;
+        (!reduced_encode_mode)) {
+        free(encode_mode);
+        free(reduced_source);
+        free(reduced_encode_mode);
+        return -1;
+    }
 
     for (i = 0; i < src_len; i++) {
         if (source[i] > 128) {
@@ -802,6 +807,10 @@ static int aztec_text_process(const unsigned char source[], const size_t src_len
         printf("Binary String:\n");
         printf("%s\n", binary_string);
     }
+
+    free(encode_mode);
+    free(reduced_source);
+    free(reduced_encode_mode);
     
     return 0;
 }
@@ -842,7 +851,7 @@ static int avoidReferenceGrid(int output) {
 
 /* Calculate the position of the bits in the grid */
 static void populate_map() {
-    int layer, start, length, n, i;
+    int layer, n, i;
     int x, y;
 
     for (x = 0; x < 151; x++) {
@@ -852,8 +861,8 @@ static void populate_map() {
     }
 
     for (layer = 1; layer < 33; layer++) {
-        start = (112 * (layer - 1)) + (16 * (layer - 1) * (layer - 1)) + 2;
-        length = 28 + ((layer - 1) * 4) + (layer * 4);
+        const int start = (112 * (layer - 1)) + (16 * (layer - 1) * (layer - 1)) + 2;
+        const int length = 28 + ((layer - 1) * 4) + (layer * 4);
         /* Top */
         i = 0;
         x = 64 - ((layer - 1) * 2);
diff --git a/backend/codablock.c b/backend/codablock.c
index d6e1524e..a99a315f 100644
--- a/backend/codablock.c
+++ b/backend/codablock.c
@@ -211,11 +211,9 @@ static int Columns2Rows(CharacterSetTable *T, unsigned char *data, const size_t
     int useColumns;     /* Usable Characters per line */
     int fillings;       /* Number of filling characters */
     int rowsCur;
-    int charCur;
     int runChar;
     int emptyColumns;   /* Number of codes still empty in line. */
     int emptyColumns2;  /* Alternative emptyColumns to compare */
-    int fOneLiner;      /* Flag if One Liner */
     int CPaires;        /* Number of digit pairs which may fit in the line */
     int characterSetCur;        /* Current Character Set */
 
@@ -226,9 +224,9 @@ static int Columns2Rows(CharacterSetTable *T, unsigned char *data, const size_t
     /* >>> Loop until rowsCur<44 */
     do {
         memset(pSet,0,dataLength*sizeof(int));
-        charCur=0;
+        int charCur=0;
         rowsCur=0;
-        fOneLiner=1;        /* First try one-Liner */
+        int fOneLiner=1;        /* First try one-Liner */
 
         /* >>> Line and OneLiner-try Loop */
         do{
@@ -433,7 +431,6 @@ static int Columns2Rows(CharacterSetTable *T, unsigned char *data, const size_t
 static int Rows2Columns(CharacterSetTable *T, unsigned char *data, const size_t dataLength,
         int * pRows, int * pUseColumns, int * pSet, int * pFillings)
 {
-    int errorCur;
     int rowsCur;
     int rowsRequested;  /* Number of requested rows */
     int backupRows = 0;
@@ -473,7 +470,7 @@ static int Rows2Columns(CharacterSetTable *T, unsigned char *data, const size_t
         pTestList[testListSize] = testColumns;
         testListSize++;
         useColumns=testColumns; /* Make a copy because it may be modified */
-        errorCur = Columns2Rows(T, data, dataLength, &rowsCur, &useColumns, pSet, &fillings);
+        int errorCur = Columns2Rows(T, data, dataLength, &rowsCur, &useColumns, pSet, &fillings);
         if (errorCur != 0)
             return errorCur;
         if (rowsCur<=rowsRequested) {
@@ -711,7 +708,7 @@ int codablock(struct zint_symbol *symbol,const unsigned char source[], const siz
             if (columns > 64)
                 columns = 64;
                 #ifdef _DEBUG
-                printf("Auto column count for %d characters:%d\n",dataLength,columns);
+                printf("Auto column count for %zu characters:%d\n",dataLength,columns);
                 #endif
         }
     }
diff --git a/backend/code.c b/backend/code.c
index cac63aec..776be7b3 100644
--- a/backend/code.c
+++ b/backend/code.c
@@ -188,7 +188,6 @@ int code_11(struct zint_symbol *symbol, unsigned char source[], int length) { /*
 int c39(struct zint_symbol *symbol, unsigned char source[], const size_t length) {
     unsigned int i;
     unsigned int counter;
-    char check_digit;
     int error_number;
     char dest[775];
     char localstr[2] = {0};
@@ -223,9 +222,10 @@ int c39(struct zint_symbol *symbol, unsigned char source[], const size_t length)
 
     if ((symbol->symbology == BARCODE_LOGMARS) || (symbol->option_2 == 1)) {
 
+        char check_digit;
         counter = counter % 43;
         if (counter < 10) {
-            check_digit = itoc(counter);
+             check_digit = itoc(counter);
         } else {
             if (counter < 36) {
                 check_digit = (counter - 10) + 'A';
@@ -465,13 +465,13 @@ int c93(struct zint_symbol *symbol, unsigned char source[], int length) {
    assume no liability for the use of this document." */
 
 void CheckCharacter() {
-    int i;
-    char part[3];
 
     if (value == target_value) {
         /* Target reached - save the generated pattern */
         strcpy(pattern, "11110");
+        int i;
         for (i = 0; i < 11; i++) {
+            char part[3];
             part[0] = itoc(S[i]);
             part[1] = itoc(B[i]);
             part[2] = '\0';
diff --git a/backend/code1.c b/backend/code1.c
index 5e5861a9..c2cb1d87 100644
--- a/backend/code1.c
+++ b/backend/code1.c
@@ -143,7 +143,7 @@ int dq4bi(unsigned char source[], int sourcelen, int position) {
 static int c1_look_ahead_test(unsigned char source[], int sourcelen, int position, int current_mode, int gs1) {
     float ascii_count, c40_count, text_count, edi_count, byte_count;
     char reduced_char;
-    int done, best_scheme, best_count, sp;
+    int done, best_scheme, sp;
 
     /* Step J */
     if (current_mode == C1_ASCII) {
@@ -285,7 +285,7 @@ static int c1_look_ahead_test(unsigned char source[], int sourcelen, int positio
 
     if (sp == sourcelen) {
         /* Step K */
-        best_count = (int) edi_count;
+        int best_count = (int) edi_count;
 
         if (text_count <= best_count) {
             best_count = (int) text_count;
@@ -303,7 +303,7 @@ static int c1_look_ahead_test(unsigned char source[], int sourcelen, int positio
         }
 
         if (byte_count <= best_count) {
-            best_count = (int) byte_count;
+            //            best_count = (int) byte_count;
             best_scheme = C1_BYTE;
         }
     } else {
@@ -361,11 +361,11 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
     sp = 0;
     tp = 0;
     latch = 0;
-    memset(c40_buffer, 0, 6);
+    memset(c40_buffer, 0, sizeof(*c40_buffer));
     c40_p = 0;
-    memset(text_buffer, 0, 6);
+    memset(text_buffer, 0, sizeof(*text_buffer));
     text_p = 0;
-    memset(edi_buffer, 0, 6);
+    memset(edi_buffer, 0, sizeof(*edi_buffer));
     edi_p = 0;
     strcpy(decimal_binary, "");
 
@@ -538,10 +538,10 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
 
         if (current_mode == C1_C40) {
             /* Step C - C40 encodation */
-            int shift_set, value, done = 0, latch = 0;
 
             next_mode = C1_C40;
             if (c40_p == 0) {
+                int done = 0;
                 if ((length - sp) >= 12) {
                     j = 0;
 
@@ -558,6 +558,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 }
 
                 if ((length - sp) >= 8) {
+                    int latch = 0;
                     j = 0;
 
                     for (i = 0; i < 8; i++) {
@@ -592,6 +593,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 target[tp] = 255; /* Unlatch */
                 tp++;
             } else {
+                int shift_set, value;
                 if (source[sp] > 127) {
                     c40_buffer[c40_p] = 1;
                     c40_p++;
@@ -639,10 +641,10 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
 
         if (current_mode == C1_TEXT) {
             /* Step D - Text encodation */
-            int shift_set, value, done = 0, latch = 0;
 
             next_mode = C1_TEXT;
             if (text_p == 0) {
+                int done = 0;
                 if ((length - sp) >= 12) {
                     j = 0;
 
@@ -659,6 +661,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 }
 
                 if ((length - sp) >= 8) {
+                    int latch = 0;
                     j = 0;
 
                     for (i = 0; i < 8; i++) {
@@ -693,6 +696,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 target[tp] = 255;
                 tp++; /* Unlatch */
             } else {
+                int shift_set, value;
                 if (source[sp] > 127) {
                     text_buffer[text_p] = 1;
                     text_p++;
@@ -740,7 +744,6 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
 
         if (current_mode == C1_EDI) {
             /* Step E - EDI Encodation */
-            int value = 0, latch = 0;
 
             next_mode = C1_EDI;
             if (edi_p == 0) {
@@ -759,6 +762,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 }
 
                 if ((length - sp) >= 8) {
+                    int latch = 0;
                     j = 0;
 
                     for (i = 0; i < 8; i++) {
@@ -792,6 +796,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 target[tp] = 255; /* Unlatch */
                 tp++;
             } else {
+                int value = 0;
                 if (source[sp] == 13) {
                     value = 0;
                 }
@@ -1179,7 +1184,7 @@ void block_copy(struct zint_symbol *symbol, char grid[][120], int start_row, int
 }
 
 int code_one(struct zint_symbol *symbol, unsigned char source[], int length) {
-    int size = 1, i, j, data_blocks;
+    int size = 1, i, j;
 
     char datagrid[136][120];
     int row, col;
@@ -1439,7 +1444,7 @@ int code_one(struct zint_symbol *symbol, unsigned char source[], int length) {
             sub_ecc[i] = 0;
         }
 
-        data_blocks = c1_blocks[size - 1];
+        int data_blocks = c1_blocks[size - 1];
 
         rs_init_gf(0x12d);
         rs_init_code(c1_ecc_blocks[size - 1], 0);
diff --git a/backend/code128.c b/backend/code128.c
index 54ccf603..b46bf422 100644
--- a/backend/code128.c
+++ b/backend/code128.c
@@ -102,16 +102,15 @@ int parunmodd(const unsigned char llyth) {
  * bring together same type blocks
  */
 void grwp(int *indexliste) {
-    int i, j;
 
     /* bring together same type blocks */
     if (*(indexliste) > 1) {
-        i = 1;
+        int i = 1;
         while (i < *(indexliste)) {
             if (list[1][i - 1] == list[1][i]) {
                 /* bring together */
                 list[0][i - 1] = list[0][i - 1] + list[0][i];
-                j = i + 1;
+                int j = i + 1;
 
                 /* decreace the list */
                 while (j < *(indexliste)) {
@@ -131,11 +130,11 @@ void grwp(int *indexliste) {
  * Implements rules from ISO 15417 Annex E
  */
 void dxsmooth(int *indexliste) {
-    int i, current, last, next, length;
+    int i, last, next;
 
     for (i = 0; i < *(indexliste); i++) {
-        current = list[1][i];
-        length = list[0][i];
+        int current = list[1][i];
+        int length = list[0][i];
         if (i != 0) {
             last = list[1][i - 1];
         } else {
diff --git a/backend/code16k.c b/backend/code16k.c
index f4578f38..9077d07c 100644
--- a/backend/code16k.c
+++ b/backend/code16k.c
@@ -89,16 +89,15 @@ static const int C16KStopValues[16] = {
 };
 
 static void grwp16(unsigned int *indexliste) {
-    int i, j;
 
     /* bring together same type blocks */
     if (*(indexliste) > 1) {
-        i = 1;
+        int i = 1;
         while(i < (int)*(indexliste)) {
             if (list[1][i - 1] == list[1][i]) {
                 /* bring together */
                 list[0][i - 1] = list[0][i - 1] + list[0][i];
-                j = i + 1;
+                int j = i + 1;
 
                 /* decreace the list */
                 while(j < (int)*(indexliste)) {
@@ -116,11 +115,11 @@ static void grwp16(unsigned int *indexliste) {
 
 /* Implements rules from ISO 15417 Annex E */
 static void dxsmooth16(unsigned int *indexliste) {
-    int i, current, last, next, length;
+    int i, last, next;
 
     for(i = 0; i < (int)*(indexliste); i++) {
-        current = list[1][i];
-        length = list[0][i];
+        int current = list[1][i];
+        int length = list[0][i];
         if (i != 0) {
             last = list[1][i - 1];
         } else {
@@ -258,10 +257,10 @@ static void c16k_set_c(const unsigned char source_a, unsigned char source_b, uns
 
 int code16k(struct zint_symbol *symbol, unsigned char source[], const size_t length) {
     char width_pattern[100];
-    int current_row, rows_needed, flip_flop, looper, first_check, second_check;
+    int current_row, rows_needed, looper, first_check, second_check;
     int indexchaine, f_state;
     char set[160] = {' '}, fset[160] = {' '}, mode, last_set, current_set;
-    unsigned int pads_needed, indexliste, i, j, k, m, read, mx_reader, writer;
+    unsigned int pads_needed, indexliste, i, j, k, m, read, mx_reader;
     unsigned int values[160] = {0};
     unsigned int bar_characters;
     float glyph_count;
@@ -705,8 +704,8 @@ int code16k(struct zint_symbol *symbol, unsigned char source[], const size_t len
         strcat(width_pattern, C16KStartStop[C16KStopValues[current_row]]);
 
         /* Write the information into the symbol */
-        writer = 0;
-        flip_flop = 1;
+        unsigned int writer = 0;
+        int flip_flop = 1;
         for (mx_reader = 0; mx_reader < strlen(width_pattern); mx_reader++) {
             for (looper = 0; looper < ctoi(width_pattern[mx_reader]); looper++) {
                 if (flip_flop == 1) {
diff --git a/backend/common.c b/backend/common.c
index 708c4172..4edaab2f 100644
--- a/backend/common.c
+++ b/backend/common.c
@@ -87,11 +87,11 @@ void to_upper(unsigned char source[]) {
 
 /* Verifies that a string only uses valid characters */
 int is_sane(const char test_string[], const unsigned char source[], const size_t length) {
-    unsigned int j, latch;
+    unsigned int j;
     size_t i, lt = strlen(test_string);
 
     for (i = 0; i < length; i++) {
-        latch = FALSE;
+        unsigned int latch = FALSE;
         for (j = 0; j < lt; j++) {
             if (source[i] == test_string[j]) {
                 latch = TRUE;
diff --git a/backend/common.h b/backend/common.h
index 4bc3fc19..2607d6a3 100644
--- a/backend/common.h
+++ b/backend/common.h
@@ -54,7 +54,7 @@
 extern "C" {
 #endif /* __cplusplus */
 
-    extern size_t ustrlen(const unsigned char source[]);
+    extern size_t ustrlen(const unsigned char data[]);
     extern int ctoi(const char source);
     extern char itoc(const int source);
     extern void to_upper(unsigned char source[]);
diff --git a/backend/composite.c b/backend/composite.c
index 842901ce..ebb54271 100644
--- a/backend/composite.c
+++ b/backend/composite.c
@@ -109,9 +109,10 @@ static void init928(void) {
 
 /* converts bit string to base 928 values, codeWords[0] is highest order */
 static int encode928(UINT bitString[], UINT codeWords[], int bitLng) {
-    int i, j, b, bitCnt, cwNdx, cwCnt, cwLng;
+    int i, j, b, cwNdx, cwLng;
     for (cwNdx = cwLng = b = 0; b < bitLng; b += 69, cwNdx += 7) {
-        bitCnt = _min(bitLng - b, 69);
+        int bitCnt = _min(bitLng - b, 69);
+        int cwCnt;
         cwLng += cwCnt = bitCnt / 10 + 1;
         for (i = 0; i < cwCnt; i++)
             codeWords[cwNdx + i] = 0; /* init 0 */
@@ -132,7 +133,7 @@ static int encode928(UINT bitString[], UINT codeWords[], int bitLng) {
 
 /* CC-A 2D component */
 static int cc_a(struct zint_symbol *symbol, char source[], int cc_width) { 
-    int i, strpos, segment, bitlen, cwCnt, variant, rows;
+    int i, segment, bitlen, cwCnt, variant, rows;
     int k, offset, j, total, rsCodeWords[8];
     int LeftRAPStart, RightRAPStart, CentreRAPStart, StartCluster;
     int LeftRAP, RightRAP, CentreRAP, Cluster, dummy[5];
@@ -162,7 +163,7 @@ static int cc_a(struct zint_symbol *symbol, char source[], int cc_width) {
     local_source[208] = '\0';
 
     for (segment = 0; segment < 13; segment++) {
-        strpos = segment * 16;
+        int strpos = segment * 16;
         for (i = 0; i < 16; i++) {
             if (local_source[strpos + i] == '1') {
                 bitStr[segment] += (0x8000 >> i);
@@ -335,7 +336,7 @@ static int cc_a(struct zint_symbol *symbol, char source[], int cc_width) {
 
 /* CC-B 2D component */
 static int cc_b(struct zint_symbol *symbol, char source[], int cc_width) { 
-    int length, i, binloc;
+    int length, i;
 #ifndef _MSC_VER
     unsigned char data_string[(strlen(source) / 8) + 3];
 #else
@@ -351,7 +352,7 @@ static int cc_b(struct zint_symbol *symbol, char source[], int cc_width) {
     length = strlen(source) / 8;
 
     for (i = 0; i < length; i++) {
-        binloc = i * 8;
+        int binloc = i * 8;
 
         data_string[i] = 0;
         for (p = 0; p < 8; p++) {
@@ -368,7 +369,7 @@ static int cc_b(struct zint_symbol *symbol, char source[], int cc_width) {
     chainemc[mclength] = 920;
     mclength++;
 
-    byteprocess(chainemc, &mclength, data_string, 0, length, 0);
+    byteprocess(chainemc, &mclength, data_string, 0, length);
 
     /* Now figure out which variant of the symbol to use and load values accordingly */
 
@@ -588,7 +589,7 @@ static int cc_b(struct zint_symbol *symbol, char source[], int cc_width) {
 
 /* CC-C 2D component - byte compressed PDF417 */
 static int cc_c(struct zint_symbol *symbol, char source[], int cc_width, int ecc_level) { 
-    int length, i, p, binloc;
+    int length, i, p;
 #ifndef _MSC_VER
     unsigned char data_string[(strlen(source) / 8) + 4];
 #else
@@ -602,7 +603,7 @@ static int cc_c(struct zint_symbol *symbol, char source[], int cc_width, int ecc
     length = strlen(source) / 8;
 
     for (i = 0; i < length; i++) {
-        binloc = i * 8;
+        int binloc = i * 8;
 
         data_string[i] = 0;
         for (p = 0; p < 8; p++) {
@@ -619,7 +620,7 @@ static int cc_c(struct zint_symbol *symbol, char source[], int cc_width, int ecc
     chainemc[mclength] = 920; /* CC-C identifier */
     mclength++;
 
-    byteprocess(chainemc, &mclength, data_string, 0, length, 0);
+    byteprocess(chainemc, &mclength, data_string, 0, length);
 
     chainemc[0] = mclength;
 
@@ -962,9 +963,7 @@ int calc_padding_ccc(int binary_length, int *cc_width, int lin_width, int *ecc)
 static int cc_binary_string(struct zint_symbol *symbol, const char source[], char binary_string[], int cc_mode, int *cc_width, int *ecc, int lin_width) { /* Handles all data encodation from section 5 of ISO/IEC 24723 */
     int encoding_method, read_posn, d1, d2, alpha_pad;
     int i, j, ai_crop, fnc1_latch;
-    long int group_val;
     int ai90_mode, latch, remainder, binary_length;
-    char date_str[4];
 #ifndef _MSC_VER
     char general_field[strlen(source) + 1], general_field_type[strlen(source) + 1];
 #else
@@ -1007,10 +1006,11 @@ static int cc_binary_string(struct zint_symbol *symbol, const char source[], cha
             read_posn = 2;
         } else {
             /* Production Date (11) or Expiration Date (17) */
+            char date_str[4];
             date_str[0] = source[2];
             date_str[1] = source[3];
             date_str[2] = '\0';
-            group_val = atoi(date_str) * 384;
+            long int group_val = atoi(date_str) * 384;
 
             date_str[0] = source[4];
             date_str[1] = source[5];
@@ -1048,9 +1048,7 @@ static int cc_binary_string(struct zint_symbol *symbol, const char source[], cha
 #else
         char* ninety = (char*) _alloca(strlen(source) + 1);
 #endif
-        char numeric_part[4];
-        int alpha, alphanum, numeric, test1, test2, test3, next_ai_posn;
-        int numeric_value, table3_letter;
+        int alpha, alphanum, numeric, test1, test2, test3;
 
         /* "This encodation method may be used if an element string with an AI
         90 occurs at the start of the data message, and if the data field
@@ -1147,7 +1145,7 @@ static int cc_binary_string(struct zint_symbol *symbol, const char source[], cha
                 }
             }
 
-            next_ai_posn = 2 + (int)strlen(ninety);
+            int next_ai_posn = 2 + (int)strlen(ninety);
 
             if (source[next_ai_posn] == '[') {
                 /* There are more AIs afterwords */
@@ -1171,6 +1169,7 @@ static int cc_binary_string(struct zint_symbol *symbol, const char source[], cha
                     break;
             }
 
+            char numeric_part[4];
             if (test1 == 0) {
                 strcpy(numeric_part, "0");
             } else {
@@ -1180,9 +1179,9 @@ static int cc_binary_string(struct zint_symbol *symbol, const char source[], cha
                 numeric_part[i] = '\0';
             }
 
-            numeric_value = atoi(numeric_part);
+            int numeric_value = atoi(numeric_part);
 
-            table3_letter = -1;
+            int table3_letter = -1;
             if (numeric_value < 31) {
                 table3_letter = posn("BDHIJKLNPQRSTVWZ", ninety[test1]);
             }
diff --git a/backend/dmatrix.c b/backend/dmatrix.c
index 0fc281de..b8c9aec9 100644
--- a/backend/dmatrix.c
+++ b/backend/dmatrix.c
@@ -194,12 +194,12 @@ static void ecc200placement(int *array, const int NR, const int NC) {
 /* calculate and append ecc code, and if necessary interleave */
 static void ecc200(unsigned char *binary, const int bytes, const int datablock, const int rsblock, const int skew) {
     int blocks = (bytes + 2) / datablock, b;
-    int n, p;
+    int n;
     rs_init_gf(0x12d);
     rs_init_code(rsblock, 1);
     for (b = 0; b < blocks; b++) {
         unsigned char buf[256], ecc[256];
-        p = 0;
+        int p = 0;
         for (n = b; n < bytes; n += blocks)
             buf[p++] = binary[n];
         rs_encode(p, buf, ecc);
@@ -698,7 +698,6 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
 
         /* step (c) C40 encodation */
         if (current_mode == DM_C40) {
-            int shift_set, value;
 
             next_mode = DM_C40;
             if (*process_p == 0) {
@@ -712,6 +711,7 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
                 next_mode = DM_ASCII;
                 if (debug) printf("ASC ");
             } else {
+                int shift_set, value;
                 if (source[sp] > 127) {
                     process_buffer[*process_p] = 1;
                     (*process_p)++;
@@ -761,7 +761,6 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
 
         /* step (d) Text encodation */
         if (current_mode == DM_TEXT) {
-            int shift_set, value;
 
             next_mode = DM_TEXT;
             if (*process_p == 0) {
@@ -775,6 +774,7 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
                 next_mode = DM_ASCII;
                 if (debug) printf("ASC ");
             } else {
+                int shift_set, value;
                 if (source[sp] > 127) {
                     process_buffer[*process_p] = 1;
                     (*process_p)++;
@@ -824,7 +824,6 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
 
         /* step (e) X12 encodation */
         if (current_mode == DM_X12) {
-            int value = 0;
 
             next_mode = DM_X12;
             if (*process_p == 0) {
@@ -838,6 +837,7 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
                 next_mode = DM_ASCII;
                 if (debug) printf("ASC ");
             } else {
+                int value = 0;
                 if (source[sp] == 13) {
                     value = 0;
                 }
@@ -885,7 +885,6 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
 
         /* step (f) EDIFACT encodation */
         if (current_mode == DM_EDIFACT) {
-            int value = 0;
 
             next_mode = DM_EDIFACT;
             if (*process_p == 3) {
@@ -897,7 +896,7 @@ static int dm200encode(struct zint_symbol *symbol, const unsigned char source[],
                 (*process_p)++;
                 next_mode = DM_ASCII;
             } else {
-                value = source[sp];
+                int value = source[sp];
                 
                 if (source[sp] >= 64) {  // '@'
                     value -= 64;
@@ -1148,7 +1147,6 @@ int data_matrix_200(struct zint_symbol *symbol,const unsigned char source[], con
     int taillength, error_number = 0;
     int H, W, FH, FW, datablock, bytes, rsblock;
     int last_mode = DM_ASCII;
-    unsigned char *grid = 0;
     int symbols_left;
 
     /* inputlen may be decremented by 2 if macro character is used */
@@ -1247,7 +1245,7 @@ int data_matrix_200(struct zint_symbol *symbol,const unsigned char source[], con
         NR = H - 2 * (H / FH);
         places = (int*) malloc(NC * NR * sizeof (int));
         ecc200placement(places, NR, NC);
-        grid = (unsigned char*) malloc(W * H);
+        unsigned char *grid = (unsigned char*) malloc(W * H);
         memset(grid, 0, W * H);
         for (y = 0; y < H; y += FH) {
             for (x = 0; x < W; x++)
diff --git a/backend/dmatrix.h b/backend/dmatrix.h
index 7d1f6415..0295355d 100644
--- a/backend/dmatrix.h
+++ b/backend/dmatrix.h
@@ -44,7 +44,7 @@
 extern "C" {
 #endif /* __cplusplus */
 
-extern int data_matrix_200(struct zint_symbol *symbol, const unsigned char source[], const size_t length);
+extern int data_matrix_200(struct zint_symbol *symbol, const unsigned char source[], const size_t in_length);
 
 #ifdef __cplusplus
 }
diff --git a/backend/dotcode.c b/backend/dotcode.c
index ce2219a4..c26b6d27 100644
--- a/backend/dotcode.c
+++ b/backend/dotcode.c
@@ -436,7 +436,7 @@ int binary(const unsigned char source[], int position) {
 int dotcode_encode_message(struct zint_symbol *symbol, const unsigned char source[], int length, unsigned char *codeword_array, int *binary_finish) {
     int input_position, array_length, i;
     char encoding_mode;
-    int inside_macro, done;
+    int inside_macro;
     int debug = symbol->debug;
     int binary_buffer_size = 0;
     int lawrencium[6]; // Reversed radix 103 values
@@ -524,7 +524,7 @@ int dotcode_encode_message(struct zint_symbol *symbol, const unsigned char sourc
     }
     
     do {
-        done = 0;
+        int done = 0;
         /* Step A */
         if ((input_position == length - 2) && (inside_macro != 0) && (inside_macro != 100)) {
             // inside_macro only gets set to 97, 98 or 99 if the last two characters are RS/EOT
@@ -1460,4 +1460,4 @@ int dotcode(struct zint_symbol *symbol, const unsigned char source[], int length
     }
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/backend/eci.c b/backend/eci.c
index 4545613d..5063cb4b 100644
--- a/backend/eci.c
+++ b/backend/eci.c
@@ -40,8 +40,6 @@
 
 /* Convert Unicode to other character encodings */
 int utf_to_eci(const int eci, const unsigned char source[], unsigned char dest[], size_t *length) {
-    int glyph;
-    int bytelen;
     int in_posn;
     int out_posn;
     int ext;
@@ -60,8 +58,8 @@ int utf_to_eci(const int eci, const unsigned char source[], unsigned char dest[]
     out_posn = 0;
     do {
         /* Single byte (ASCII) character */
-        bytelen = 1;
-        glyph = (int) source[in_posn];
+        int bytelen = 1;
+        int glyph = (int) source[in_posn];
 
         if ((source[in_posn] >= 0x80) && (source[in_posn] < 0xc0)) {
             /* Something has gone wrong, abort */
diff --git a/backend/emf.c b/backend/emf.c
index 94c1425e..31199d53 100644
--- a/backend/emf.c
+++ b/backend/emf.c
@@ -43,13 +43,12 @@
 
 int count_rectangles(struct zint_symbol *symbol) {
     int rectangles = 0;
-    int this_row;
-    int latch, i;
     
     if ((symbol->symbology != BARCODE_MAXICODE) && 
             ((symbol->output_options & BARCODE_DOTTY_MODE) == 0)) {
+        int this_row;
         for(this_row = 0; this_row < symbol->rows; this_row++) {
-            latch = 0;
+            int i, latch = 0;
             for(i = 0; i < symbol->width; i++) {
                 if ((module_is_set(symbol, this_row, i)) && (latch == 0)) {
                     latch = 1;
@@ -68,12 +67,12 @@ int count_rectangles(struct zint_symbol *symbol) {
 
 int count_circles(struct zint_symbol *symbol) {
     int circles = 0;
-    int this_row;
-    int i;
     
     if ((symbol->symbology != BARCODE_MAXICODE) &&
             ((symbol->output_options & BARCODE_DOTTY_MODE) != 0)) {
+        int this_row;
         for(this_row = 0; this_row < symbol->rows; this_row++) {
+            int i;
             for(i = 0; i < symbol->width; i++) {
                 if (module_is_set(symbol, this_row, i)) {
                     circles++;
@@ -87,11 +86,11 @@ int count_circles(struct zint_symbol *symbol) {
 
 int count_hexagons(struct zint_symbol *symbol) {
     int hexagons = 0;
-    int this_row;
-    int i;
     
     if (symbol->symbology == BARCODE_MAXICODE) {
+        int this_row;
         for(this_row = 0; this_row < symbol->rows; this_row++) {
+            int i;
             for(i = 0; i < symbol->width; i++) {
                 if (module_is_set(symbol, this_row, i)) {
                     hexagons++;
@@ -137,7 +136,7 @@ int bump_up(int input) {
 
 int emf_plot(struct zint_symbol *symbol) {
     int i, block_width, latch, this_row;
-    float large_bar_height, preset_height, row_height, row_posn;
+    float large_bar_height, preset_height, row_height;
     FILE *emf_file;
     int fgred, fggrn, fgblu, bgred, bggrn, bgblu;
     int error_number = 0;
@@ -751,7 +750,7 @@ int emf_plot(struct zint_symbol *symbol) {
         } else {
             row_height = symbol->row_height[this_row];
         }
-        row_posn = 0;
+        float row_posn = 0;
         for (i = 0; i < this_row; i++) {
             if (symbol->row_height[i] == 0) {
                 row_posn += large_bar_height;
diff --git a/backend/gridmtx.c b/backend/gridmtx.c
index b77a05b7..c7a62e18 100644
--- a/backend/gridmtx.c
+++ b/backend/gridmtx.c
@@ -49,13 +49,13 @@ int number_lat(int gbdata[], const size_t length, const size_t position) {
        a string which has "2.2.0" (cannot have more than one non-numeric character for each
        block of three numeric characters) */
     size_t sp;
-    int numb = 0, nonum = 0, done;
+    int numb = 0, nonum = 0;
     int tally = 0;
 
     sp = position;
 
     do {
-        done = 0;
+        int done = 0;
 
         if ((gbdata[sp] >= '0') && (gbdata[sp] <= '9')) {
             numb++;
@@ -125,7 +125,7 @@ static int seek_forward(int gbdata[], const size_t length, const size_t position
        possible combinations of input data */
 
     int number_count, byte_count, mixed_count, upper_count, lower_count, chinese_count;
-    int    best_mode, done;
+    int    best_mode;
    size_t sp;
     int best_count, last = -1;
     int debug = 0;
@@ -194,7 +194,7 @@ static int seek_forward(int gbdata[], const size_t length, const size_t position
 
     for (sp = position; (sp < length) && (sp <= (position + 8)); sp++) {
 
-        done = 0;
+        int done = 0;
 
         if (gbdata[sp] >= 0xff) {
             byte_count += 17;
@@ -347,7 +347,7 @@ static int gm_encode(int gbdata[], const size_t length, char binary[],const int
     /* Create a binary stream representation of the input data.
        7 sets are defined - Chinese characters, Numerals, Lower case letters, Upper case letters,
        Mixed numerals and latters, Control characters and 8-bit binary data */
-    int sp, current_mode, next_mode, last_mode, glyph = 0;
+    int sp, current_mode, last_mode, glyph = 0;
     int c1, c2, done;
     int p = 0, ppos;
     int numbuf[3], punt = 0;
@@ -383,7 +383,7 @@ static int gm_encode(int gbdata[], const size_t length, char binary[],const int
     }
 
     do {
-        next_mode = seek_forward(gbdata, length, sp, current_mode);
+        int next_mode = seek_forward(gbdata, length, sp, current_mode);
 
         if (next_mode != current_mode) {
             switch (current_mode) {
@@ -800,7 +800,7 @@ static int gm_encode(int gbdata[], const size_t length, char binary[],const int
 static void gm_add_ecc(const char binary[], const size_t data_posn, const int layers, const int ecc_level, int word[]) {
     int data_cw, i, j, wp, p;
     int n1, b1, n2, b2, e1, b3, e2;
-    int block_size, data_size, ecc_size;
+    int block_size, ecc_size;
     int data[1320], block[130];
     unsigned char data_block[115], ecc_block[70];
 
@@ -851,7 +851,7 @@ static void gm_add_ecc(const char binary[], const size_t data_posn, const int la
         } else {
             ecc_size = e2;
         }
-        data_size = block_size - ecc_size;
+        int data_size = block_size - ecc_size;
 
         /* printf("block %d/%d: data %d / ecc %d\n", i + 1, (b1 + b2), data_size, ecc_size);*/
 
@@ -1000,9 +1000,9 @@ void place_layer_id(char* grid, int size, int layers, int modules, int ecc_level
 }
 
 int grid_matrix(struct zint_symbol *symbol, const unsigned char source[], size_t length) {
-    int size, modules, dark, error_number;
+    int size, modules, error_number;
     int auto_layers, min_layers, layers, auto_ecc_level, min_ecc_level, ecc_level;
-    int x, y, i, j, glyph;
+    int x, y, i;
     char binary[9300];
     int data_cw, input_latch = 0;
     int word[1460], data_max, reader = 0;
@@ -1035,8 +1035,8 @@ int grid_matrix(struct zint_symbol *symbol, const unsigned char source[], size_t
             if (utfdata[i] <= 0xff) {
                 gbdata[i] = utfdata[i];
             } else {
-                j = 0;
-                glyph = 0;
+                int j = 0;
+                int glyph = 0;
                 do {
                     if (gb2312_lookup[j * 2] == utfdata[i]) {
                         glyph = gb2312_lookup[(j * 2) + 1];
@@ -1174,7 +1174,7 @@ int grid_matrix(struct zint_symbol *symbol, const unsigned char source[], size_t
 
     /* Add macromodule frames */
     for (x = 0; x < modules; x++) {
-        dark = 1 - (x & 1);
+        int dark = 1 - (x & 1);
         for (y = 0; y < modules; y++) {
             if (dark == 1) {
                 for (i = 0; i < 5; i++) {
diff --git a/backend/hanxin.c b/backend/hanxin.c
index 2b99650e..e4f8f168 100644
--- a/backend/hanxin.c
+++ b/backend/hanxin.c
@@ -228,11 +228,10 @@ int isFourByte(int glyph, int glyph2) {
 static void hx_define_mode(char mode[], int source[], const size_t length) {
     size_t i;
     char lastmode = 't';
-    int done;
-    
+
     i = 0;
     do {
-        done = 0;
+        int done = 0;
         
         if (isRegion1(source[i])) {
             mode[i] = '1';
@@ -330,7 +329,6 @@ int lookup_text2(char input) {
 
 /* Convert input data to binary stream */
 static void calculate_binary(char binary[], char mode[], int source[], const size_t length, const int eci, int debug) {
-    int block_length;
     int position = 0;
     int i, count, encoding_value;
     int first_byte, second_byte;
@@ -355,7 +353,7 @@ static void calculate_binary(char binary[], char mode[], int source[], const siz
     }
 
     do {
-        block_length = 0;
+        int block_length = 0;
         do {
             block_length++;
         } while (mode[position + block_length] == mode[position]);
@@ -373,19 +371,19 @@ static void calculate_binary(char binary[], char mode[], int source[], const siz
                 i = 0;
 
                 while (i < block_length) {
-                    int first = 0, second = 0, third = 0;
+                    int first = 0;
 
                     first = posn(NEON, (char) source[position + i]);
                     count = 1;
                     encoding_value = first;
 
                     if (i + 1 < block_length && mode[position + i + 1] == 'n') {
-                        second = posn(NEON, (char) source[position + i + 1]);
+                        int second = posn(NEON, (char) source[position + i + 1]);
                         count = 2;
                         encoding_value = (encoding_value * 10) + second;
 
                         if (i + 2 < block_length && mode[position + i + 2] == 'n') {
-                            third = posn(NEON, (char) source[position + i + 2]);
+                            int third = posn(NEON, (char) source[position + i + 2]);
                             count = 3;
                             encoding_value = (encoding_value * 10) + third;
                         }
@@ -910,15 +908,14 @@ void hx_add_ecc(unsigned char fullstream[], unsigned char datastream[], int vers
     unsigned char data_block[180];
     unsigned char ecc_block[36];
     int i, j, block;
-    int batch_size, data_length, ecc_length;
     int input_position = -1;
     int output_position = -1;
     int table_d1_pos = ((version - 1) * 36) + ((ecc_level - 1) * 9);
 
     for (i = 0; i < 3; i++) {
-        batch_size = hx_table_d1[table_d1_pos + (3 * i)];
-        data_length = hx_table_d1[table_d1_pos + (3 * i) + 1];
-        ecc_length = hx_table_d1[table_d1_pos + (3 * i) + 2];
+        int batch_size = hx_table_d1[table_d1_pos + (3 * i)];
+        int data_length = hx_table_d1[table_d1_pos + (3 * i) + 1];
+        int ecc_length = hx_table_d1[table_d1_pos + (3 * i) + 2];
 
         for (block = 0; block < batch_size; block++) {
             for (j = 0; j < data_length; j++) {
@@ -1228,13 +1225,11 @@ int hx_apply_bitmask(unsigned char *grid, int size) {
 int han_xin(struct zint_symbol *symbol, const unsigned char source[], size_t length) {
     int est_binlen;
     int ecc_level = symbol->option_1;
-    int i, j, version, posn = 0;
+    int i, j, version;
     int data_codewords = 0, size;
     int codewords;
     int bitmask;
-    int error_number;
     int bin_len;
-    int done;
     char function_information[36];
     unsigned char fi_cw[3] = {0, 0, 0};
     unsigned char fi_ecc[4];
@@ -1260,14 +1255,14 @@ int han_xin(struct zint_symbol *symbol, const unsigned char source[], size_t len
         }
     } else {
         /* Convert Unicode input to GB-18030 */
-        error_number = utf8toutf16(symbol, source, utfdata, &length);
+        int error_number = utf8toutf16(symbol, source, utfdata, &length);
         if (error_number != 0) {
             return error_number;
         }
 
-        posn = 0;
+        int posn = 0;
         for (i = 0; i < length; i++) {
-            done = 0;
+            int done = 0;
             gbdata[posn] = 0;
             
             /* Single byte characters in range U+0000 -> U+007F */
diff --git a/backend/large.c b/backend/large.c
index dda4d5f1..79ff4871 100644
--- a/backend/large.c
+++ b/backend/large.c
@@ -36,11 +36,11 @@
 #include "large.h"
 
 void binary_add(short int accumulator[], short int input_buffer[]) { /* Binary addition */
-    int i, carry, done;
+    int i, carry;
     carry = 0;
 
     for (i = 0; i < 112; i++) {
-        done = 0;
+        int done = 0;
         if (((input_buffer[i] == 0) && (accumulator[i] == 0)) 
                 && ((carry == 0) && (done == 0))) {
             accumulator[i] = 0;
diff --git a/backend/library.c b/backend/library.c
index 9c2eb6e6..8fbb2b4e 100644
--- a/backend/library.c
+++ b/backend/library.c
@@ -102,22 +102,22 @@ void ZBarcode_Delete(struct zint_symbol *symbol) {
 
     // If there is a rendered version, ensure its memory is released
     if (symbol->rendered != NULL) {
-        struct zint_render_line *line, *l;
-        struct zint_render_string *string, *s;
-        struct zint_render_ring *ring, *r;
-        struct zint_render_hexagon *hexagon, *h;
+        struct zint_render_line *line;
+        struct zint_render_string *string;
+        struct zint_render_ring *ring;
+        struct zint_render_hexagon *hexagon;
 
         // Free lines
         line = symbol->rendered->lines;
         while (line) {
-            l = line;
+            struct zint_render_line *l = line;
             line = line->next;
             free(l);
         }
         // Free Strings
         string = symbol->rendered->strings;
         while (string) {
-            s = string;
+            struct zint_render_string *s = string;
             string = string->next;
             free(s->text);
             free(s);
@@ -126,7 +126,7 @@ void ZBarcode_Delete(struct zint_symbol *symbol) {
         // Free Rings
         ring = symbol->rendered->rings;
         while (ring) {
-            r = ring;
+            struct zint_render_ring *r = ring;
             ring = ring->next;
             free(r);
         }
@@ -134,7 +134,7 @@ void ZBarcode_Delete(struct zint_symbol *symbol) {
         // Free Hexagons
         hexagon = symbol->rendered->hexagons;
         while (hexagon) {
-            h = hexagon;
+            struct zint_render_hexagon *h = hexagon;
             hexagon = hexagon->next;
             free(h);
         }
@@ -215,9 +215,9 @@ extern int svg_plot(struct zint_symbol *symbol); /* Plot to SVG */
 extern int emf_plot(struct zint_symbol *symbol); /* Plot to Metafile */
 
 void error_tag(char error_string[], int error_number) {
-    char error_buffer[100];
 
     if (error_number != 0) {
+        char error_buffer[100];
         strcpy(error_buffer, error_string);
 
         if (error_number > 4) {
@@ -234,7 +234,6 @@ void error_tag(char error_string[], int error_number) {
 int dump_plot(struct zint_symbol *symbol) {
     FILE *f;
     int i, r;
-    int byt;
     char hex[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8',
         '9', 'A', 'B', 'C', 'D', 'E', 'F'};
     int space = 0;
@@ -250,7 +249,7 @@ int dump_plot(struct zint_symbol *symbol) {
     }
 
     for (r = 0; r < symbol->rows; r++) {
-        byt = 0;
+        int byt = 0;
         for (i = 0; i < symbol->width; i++) {
             byt = byt << 1;
             if (module_is_set(symbol, r, i)) {
@@ -1083,7 +1082,6 @@ int ZBarcode_Encode(struct zint_symbol *symbol, const unsigned char *source,int
 
 int ZBarcode_Print(struct zint_symbol *symbol, int rotate_angle) {
     int error_number;
-    char output[4];
 
     switch (rotate_angle) {
         case 0:
@@ -1104,6 +1102,7 @@ int ZBarcode_Print(struct zint_symbol *symbol, int rotate_angle) {
     }
 
     if (strlen(symbol->outfile) > 3) {
+        char output[4];
         output[0] = symbol->outfile[strlen(symbol->outfile) - 3];
         output[1] = symbol->outfile[strlen(symbol->outfile) - 2];
         output[2] = symbol->outfile[strlen(symbol->outfile) - 1];
diff --git a/backend/maxicode.c b/backend/maxicode.c
index a0123673..59c36e7c 100644
--- a/backend/maxicode.c
+++ b/backend/maxicode.c
@@ -588,8 +588,8 @@ void maxi_do_primary_3(char postcode[], int country, int service) {
     maxi_codeword[9] = ((service & 0x3f0) >> 4);
 }
 
-int maxicode(struct zint_symbol *symbol, unsigned char local_source[], int length) {
-    int i, j, block, bit, mode, countrycode = 0, service = 0, lp = 0;
+int maxicode(struct zint_symbol *symbol, unsigned char local_source[], const int length) {
+    int i, j, block, bit, mode, lp = 0;
     int bit_pattern[7], internal_error = 0, eclen;
     char postcode[12], countrystr[4], servicestr[4];
 
@@ -659,8 +659,8 @@ int maxicode(struct zint_symbol *symbol, unsigned char local_source[], int lengt
         servicestr[2] = symbol->primary[14];
         servicestr[3] = '\0';
 
-        countrycode = atoi(countrystr);
-        service = atoi(servicestr);
+        int countrycode = atoi(countrystr);
+        int service = atoi(servicestr);
 
         if (mode == 2) {
             maxi_do_primary_2(postcode, countrycode, service);
diff --git a/backend/medical.c b/backend/medical.c
index 94bd72a3..ffd79c9b 100644
--- a/backend/medical.c
+++ b/backend/medical.c
@@ -235,7 +235,7 @@ int codabar(struct zint_symbol *symbol, unsigned char source[], int length) {
 int code32(struct zint_symbol *symbol, unsigned char source[], int length) {
     int i, zeroes, error_number, checksum, checkpart, checkdigit;
     char localstr[10], risultante[7];
-    long int pharmacode, remainder, devisor;
+    long int pharmacode, devisor;
     int codeword[6];
     char tabella[34];
 
@@ -281,7 +281,7 @@ int code32(struct zint_symbol *symbol, unsigned char source[], int length) {
     devisor = 33554432;
     for (i = 5; i >= 0; i--) {
         codeword[i] = pharmacode / devisor;
-        remainder = pharmacode % devisor;
+        long int remainder = pharmacode % devisor;
         pharmacode = remainder;
         devisor /= 32;
     }
diff --git a/backend/pdf417.c b/backend/pdf417.c
index ca64578c..df1deb03 100644
--- a/backend/pdf417.c
+++ b/backend/pdf417.c
@@ -101,16 +101,15 @@ int quelmode(char codeascii) {
 
 /* 844 */
 void regroupe(int *indexliste) {
-    int i, j;
 
     /* bring together same type blocks */
     if (*(indexliste) > 1) {
-        i = 1;
+        int i = 1;
         while (i < *(indexliste)) {
             if (liste[1][i - 1] == liste[1][i]) {
                 /* bring together */
                 liste[0][i - 1] = liste[0][i - 1] + liste[0][i];
-                j = i + 1;
+                int j = i + 1;
 
                 /* decreace the list */
                 while (j < *(indexliste)) {
@@ -224,11 +223,9 @@ void pdfsmooth(int *indexliste) {
 }
 
 /* 547 */
-void textprocess(int *chainemc, int *mclength, char chaine[], int start, int length, int block) {
+void textprocess(int *chainemc, int *mclength, char chaine[], int start, int length) {
     int j, indexlistet, curtable, listet[2][5000], chainet[5000], wnet;
-    char codeascii;
 
-    codeascii = 0;
     wnet = 0;
 
     for (j = 0; j < 1000; j++) {
@@ -236,7 +233,7 @@ void textprocess(int *chainemc, int *mclength, char chaine[], int start, int len
     }
     /* listet will contain the table numbers and the value of each characters */
     for (indexlistet = 0; indexlistet < length; indexlistet++) {
-        codeascii = chaine[start + indexlistet];
+        char codeascii = chaine[start + indexlistet];
         switch (codeascii) {
             case '\t': listet[0][indexlistet] = 12;
                 listet[1][indexlistet] = 12;
@@ -417,17 +414,8 @@ void textprocess(int *chainemc, int *mclength, char chaine[], int start, int len
 }
 
 /* 671 */
-void byteprocess(int *chainemc, int *mclength, unsigned char chaine[], int start, int length, int block) {
+void byteprocess(int *chainemc, int *mclength, unsigned char chaine[], int start, int length) {
     int debug = 0;
-    int len = 0;
-    unsigned int chunkLen = 0;
-#if defined(_MSC_VER) && _MSC_VER == 1200
-    uint64_t mantisa = 0;
-    uint64_t total = 0;
-#else
-    uint64_t mantisa = 0ULL;
-    uint64_t total = 0ULL;
-#endif
 
     if (debug) printf("\nEntering byte mode at position %d\n", start);
 
@@ -447,19 +435,21 @@ void byteprocess(int *chainemc, int *mclength, unsigned char chaine[], int start
             if (debug) printf("901 ");
         }
 
+        int len = 0;
+
         while (len < length) {
-            chunkLen = length - len;
+            unsigned int chunkLen = length - len;
             if (6 <= chunkLen) /* Take groups of 6 */ {
                 chunkLen = 6;
                 len += chunkLen;
 #if defined(_MSC_VER) && _MSC_VER == 1200
-                total = 0;
+                uint64_t total = 0;
 #else
-                total = 0ULL;
+                uint64_t total = 0ULL;
 #endif
 
                 while (chunkLen--) {
-                    mantisa = chaine[start++];
+                    uint64_t mantisa = chaine[start++];
 #if defined(_MSC_VER) && _MSC_VER == 1200
                     total |= mantisa << (uint64_t) (chunkLen * 8);
 #else
@@ -490,8 +480,8 @@ void byteprocess(int *chainemc, int *mclength, unsigned char chaine[], int start
 }
 
 /* 712 */
-void numbprocess(int *chainemc, int *mclength, char chaine[], int start, int length, int block) {
-    int j, loop, longueur, dummy[100], dumlength, diviseur, nombre;
+void numbprocess(int *chainemc, int *mclength, char chaine[], int start, int length) {
+    int j, loop, dummy[100], diviseur, nombre;
     char chainemod[50], chainemult[100], temp;
 
     strcpy(chainemod, "");
@@ -504,9 +494,9 @@ void numbprocess(int *chainemc, int *mclength, char chaine[], int start, int len
 
     j = 0;
     while (j < length) {
-        dumlength = 0;
+        int dumlength = 0;
         strcpy(chainemod, "");
-        longueur = length - j;
+        int longueur = length - j;
         if (longueur > 44) {
             longueur = 44;
         }
@@ -645,13 +635,13 @@ static int pdf417(struct zint_symbol *symbol, unsigned char chaine[], const size
     for (i = 0; i < indexliste; i++) {
         switch (liste[1][i]) {
             case TEX: /* 547 - text mode */
-                textprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i], i);
+                textprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i]);
                 break;
             case BYT: /* 670 - octet stream mode */
-                byteprocess(chainemc, &mclength, chaine, indexchaine, liste[0][i], i);
+                byteprocess(chainemc, &mclength, chaine, indexchaine, liste[0][i]);
                 break;
             case NUM: /* 712 - numeric mode */
-                numbprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i], i);
+                numbprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i]);
                 break;
         }
         indexchaine = indexchaine + liste[0][i];
@@ -974,13 +964,13 @@ int micro_pdf417(struct zint_symbol *symbol, unsigned char chaine[], const size_
     for (i = 0; i < indexliste; i++) {
         switch (liste[1][i]) {
             case TEX: /* 547 - text mode */
-                textprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i], i);
+                textprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i]);
                 break;
             case BYT: /* 670 - octet stream mode */
-                byteprocess(chainemc, &mclength, chaine, indexchaine, liste[0][i], i);
+                byteprocess(chainemc, &mclength, chaine, indexchaine, liste[0][i]);
                 break;
             case NUM: /* 712 - numeric mode */
-                numbprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i], i);
+                numbprocess(chainemc, &mclength, (char*) chaine, indexchaine, liste[0][i]);
                 break;
         }
         indexchaine = indexchaine + liste[0][i];
diff --git a/backend/pdf417.h b/backend/pdf417.h
index 2c2f5517..90e8b4ac 100644
--- a/backend/pdf417.h
+++ b/backend/pdf417.h
@@ -511,4 +511,4 @@ static const unsigned short int rap_centre[52] = {
     0x2DC, 0x2DE
 };
 
-void byteprocess(int *chainemc, int *mclength, unsigned char chaine[], int start, int length, int block);
\ No newline at end of file
+void byteprocess(int *chainemc, int *mclength, unsigned char chaine[], int start, int length);
\ No newline at end of file
diff --git a/backend/plessey.c b/backend/plessey.c
index 11548451..68ed2007 100644
--- a/backend/plessey.c
+++ b/backend/plessey.c
@@ -51,7 +51,7 @@ static const char *MSITable[10] = {
 /* Not MSI/Plessey but the older Plessey standard */
 int plessey(struct zint_symbol *symbol, unsigned char source[], const size_t length) { 
 
-    unsigned int i, check;
+    unsigned int i;
     unsigned char *checkptr;
     static const char grid[9] = {1, 1, 1, 1, 0, 1, 0, 0, 1};
     char dest[1024]; /* 8 + 65 * 8 + 8 * 2 + 9 + 1 ~ 1024 */
@@ -73,7 +73,7 @@ int plessey(struct zint_symbol *symbol, unsigned char source[], const size_t len
 
     /* Data area */
     for (i = 0; i < length; i++) {
-        check = posn(SSET, source[i]);
+        unsigned int check = posn(SSET, source[i]);
         lookup(SSET, PlessTable, source[i], dest);
         checkptr[4 * i] = check & 1;
         checkptr[4 * i + 1] = (check >> 1) & 1;
@@ -85,10 +85,11 @@ int plessey(struct zint_symbol *symbol, unsigned char source[], const size_t len
        used in GNU Barcode */
 
     for (i = 0; i < (4 * length); i++) {
-        int j;
-        if (checkptr[i])
+        if (checkptr[i]) {
+            int j;
             for (j = 0; j < 9; j++)
                 checkptr[i + j] ^= grid[j];
+        }
     }
 
     for (i = 0; i < 8; i++) {
@@ -171,7 +172,7 @@ int msi_plessey_mod10(struct zint_symbol *symbol, unsigned char source[], int le
     dau = strtoul(un, NULL, 10);
     dau *= 2;
 
-    sprintf(tri, "%ld", dau);
+    sprintf(tri, "%lu", dau);
 
     pedwar = 0;
     h = strlen(tri);
@@ -240,7 +241,7 @@ int msi_plessey_mod1010(struct zint_symbol *symbol, unsigned char source[], cons
     dau = strtoul(un, NULL, 10);
     dau *= 2;
 
-    sprintf(tri, "%ld", dau);
+    sprintf(tri, "%lu", dau);
 
     pedwar = 0;
     h = strlen(tri);
@@ -270,7 +271,7 @@ int msi_plessey_mod1010(struct zint_symbol *symbol, unsigned char source[], cons
     dau = strtoul(un, NULL, 10);
     dau *= 2;
 
-    sprintf(tri, "%ld", dau);
+    sprintf(tri, "%lu", dau);
 
     pedwar = 0;
     h = strlen(tri);
@@ -428,7 +429,7 @@ int msi_plessey_mod1110(struct zint_symbol *symbol, unsigned char source[], cons
     dau = strtoul(un, NULL, 10);
     dau *= 2;
 
-    sprintf(tri, "%ld", dau);
+    sprintf(tri, "%lu", dau);
 
     pedwar = 0;
     h = strlen(tri);
diff --git a/backend/png.c b/backend/png.c
index a726d516..12fe6762 100644
--- a/backend/png.c
+++ b/backend/png.c
@@ -76,7 +76,6 @@ int png_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
     struct mainprog_info_type *graphic;
     png_structp png_ptr;
     png_infop info_ptr;
-    unsigned char *image_data;
     int i, row, column;
     int fgred, fggrn, fgblu, bgred, bggrn, bgblu;
 
@@ -172,7 +171,7 @@ int png_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
             }
         }
         /* write row contents to file */
-        image_data = outdata;
+        unsigned char *image_data = outdata;
         png_write_row(png_ptr, image_data);
     }
 
diff --git a/backend/ps.c b/backend/ps.c
index 60b05a4a..c4bcddf7 100644
--- a/backend/ps.c
+++ b/backend/ps.c
@@ -40,8 +40,8 @@
 #define SSET	"0123456789ABCDEF"
 
 int ps_plot(struct zint_symbol *symbol) {
-    int i, block_width, latch, r, this_row;
-    float textpos, large_bar_height, preset_height, row_height, row_posn;
+    int i, block_width, latch, r;
+    float textpos, large_bar_height, preset_height, row_height;
     FILE *feps;
     int fgred, fggrn, fgblu, bgred, bggrn, bgblu;
     float red_ink, green_ink, blue_ink, red_paper, green_paper, blue_paper;
@@ -383,7 +383,7 @@ int ps_plot(struct zint_symbol *symbol) {
                     ey = my - 0.5 + yoffset;
                     fy = my + 0.5 + yoffset;
 
-                    mx = 2.46 * i + 1.23 + (r & 1 ? 1.23 : 0);
+                    mx = 2.46 * i + 1.23 + ((r & 1) ? 1.23 : 0);
 
                     ax = mx + xoffset;
                     bx = mx + 0.86 + xoffset;
@@ -404,13 +404,13 @@ int ps_plot(struct zint_symbol *symbol) {
         int addon_latch = 0;
 
         for (r = 0; r < symbol->rows; r++) {
-            this_row = symbol->rows - r - 1; /* invert r otherwise plots upside down */
+            int this_row = symbol->rows - r - 1; /* invert r otherwise plots upside down */
             if (symbol->row_height[this_row] == 0) {
                 row_height = large_bar_height;
             } else {
                 row_height = symbol->row_height[this_row];
             }
-            row_posn = 0;
+            float row_posn = 0;
             for (i = 0; i < r; i++) {
                 if (symbol->row_height[symbol->rows - i - 1] == 0) {
                     row_posn += large_bar_height;
diff --git a/backend/qr.c b/backend/qr.c
index b6aabc4a..f2f70709 100644
--- a/backend/qr.c
+++ b/backend/qr.c
@@ -149,8 +149,8 @@ static int tribus(const int version,const int a,const int b,const int c) {
 /* Convert input data to a binary stream and add padding */
 static void qr_binary(int datastream[], const int version, const int target_binlen, const char mode[], const int jisdata[], const size_t length, const int gs1, const int eci, const int est_binlen,const int debug) {
     int position = 0;
-    int short_data_block_length, i;
-    char data_block, padbits;
+    int i;
+    char padbits;
     int current_binlen, current_bytes;
     int toggle, percent;
 
@@ -186,8 +186,8 @@ static void qr_binary(int datastream[], const int version, const int target_binl
     percent = 0;
 
     do {
-        data_block = mode[position];
-        short_data_block_length = 0;
+        char data_block = mode[position];
+        int short_data_block_length = 0;
         do {
             short_data_block_length++;
         } while (((short_data_block_length + position) < length)
@@ -370,19 +370,19 @@ static void qr_binary(int datastream[], const int version, const int target_binl
                 i = 0;
                 while (i < short_data_block_length) {
                     int count;
-                    int first = 0, second = 0, third = 0, prod;
+                    int first = 0, prod;
 
                     first = posn(NEON, (char) jisdata[position + i]);
                     count = 1;
                     prod = first;
 
                     if (i + 1 < short_data_block_length && mode[position + i + 1] == 'N') {
-                        second = posn(NEON, (char) jisdata[position + i + 1]);
+                        int second = posn(NEON, (char) jisdata[position + i + 1]);
                         count = 2;
                         prod = (prod * 10) + second;
 
                         if (i + 2 < short_data_block_length && mode[position + i + 2] == 'N') {
-                            third = posn(NEON, (char) jisdata[position + i + 2]);
+                            int third = posn(NEON, (char) jisdata[position + i + 2]);
                             count = 3;
                             prod = (prod * 10) + third;
                         }
@@ -579,7 +579,6 @@ static void place_align(unsigned char grid[],const int size,int x,int y) {
 
 static void setup_grid(unsigned char* grid,const int size,const int version) {
     int i, toggle = 1;
-    int loopsize, x, y, xcoord, ycoord;
 
     /* Add timing patterns */
     for (i = 0; i < size; i++) {
@@ -616,11 +615,12 @@ static void setup_grid(unsigned char* grid,const int size,const int version) {
     if (version != 1) {
         /* Version 1 does not have alignment patterns */
 
-        loopsize = qr_align_loopsize[version - 1];
+        int loopsize = qr_align_loopsize[version - 1];
+        int x, y;
         for (x = 0; x < loopsize; x++) {
             for (y = 0; y < loopsize; y++) {
-                xcoord = qr_table_e1[((version - 2) * 7) + x];
-                ycoord = qr_table_e1[((version - 2) * 7) + y];
+                int xcoord = qr_table_e1[((version - 2) * 7) + x];
+                int ycoord = qr_table_e1[((version - 2) * 7) + y];
 
                 if (!(grid[(ycoord * size) + xcoord] & 0x10)) {
                     place_align(grid, size, xcoord, ycoord);
@@ -666,13 +666,13 @@ static void populate_grid(unsigned char* grid,const int size,const int* datastre
     int direction = 1; /* up */
     int row = 0; /* right hand side */
 
-    int i, n, x, y;
+    int i, n, y;
 
     n = cw * 8;
     y = size - 1;
     i = 0;
     do {
-        x = (size - 2) - (row * 2);
+        int x = (size - 2) - (row * 2);
         if (x < 6)
             x--; /* skip over vertical timing pattern */
 
@@ -1005,24 +1005,24 @@ static void add_format_info_eval(unsigned char *eval,const int size,const int ec
     seq = qr_annex_c[format];
 
     for (i = 0; i < 6; i++) {
-        eval[(i * size) + 8] = (seq >> i) & 0x01 ? (0x01 >> pattern) : 0x00;
+        eval[(i * size) + 8] = ((seq >> i) & 0x01) ? (0x01 >> pattern) : 0x00;
     }
 
     for (i = 0; i < 8; i++) {
-        eval[(8 * size) + (size - i - 1)] = (seq >> i) & 0x01 ? (0x01 >> pattern) : 0x00;
+        eval[(8 * size) + (size - i - 1)] = ((seq >> i) & 0x01) ? (0x01 >> pattern) : 0x00;
     }
 
     for (i = 0; i < 6; i++) {
-        eval[(8 * size) + (5 - i)] = (seq >> (i + 9)) & 0x01 ? (0x01 >> pattern) : 0x00;
+        eval[(8 * size) + (5 - i)] = ((seq >> (i + 9)) & 0x01) ? (0x01 >> pattern) : 0x00;
     }
 
     for (i = 0; i < 7; i++) {
-        eval[(((size - 7) + i) * size) + 8] = (seq >> (i + 8)) & 0x01 ? (0x01 >> pattern) : 0x00;
+        eval[(((size - 7) + i) * size) + 8] = ((seq >> (i + 8)) & 0x01) ? (0x01 >> pattern) : 0x00;
     }
 
-    eval[(7 * size) + 8] = (seq >> 6) & 0x01 ? (0x01 >> pattern) : 0x00;
-    eval[(8 * size) + 8] = (seq >> 7) & 0x01 ? (0x01 >> pattern) : 0x00;
-    eval[(8 * size) + 7] = (seq >> 8) & 0x01 ? (0x01 >> pattern) : 0x00;
+    eval[(7 * size) + 8] = ((seq >> 6) & 0x01) ? (0x01 >> pattern) : 0x00;
+    eval[(8 * size) + 8] = ((seq >> 7) & 0x01) ? (0x01 >> pattern) : 0x00;
+    eval[(8 * size) + 7] = ((seq >> 8) & 0x01) ? (0x01 >> pattern) : 0x00;
 }
 
 static int apply_bitmask(unsigned char *grid,const int size,const int ecc_level) {
@@ -1388,7 +1388,6 @@ static int getBinaryLength(const int version,char inputMode[],const int inputDat
 
 int qr_code(struct zint_symbol *symbol, const unsigned char source[], size_t length) {
     int i, j, est_binlen;
-    int error_number,glyph;
     int ecc_level, autosize, version, max_cw, target_binlen, blocks, size;
     int bitmask, gs1;
     int canShrink;
@@ -1414,7 +1413,7 @@ int qr_code(struct zint_symbol *symbol, const unsigned char source[], size_t len
         }
     } else {
         /* Convert Unicode input to Shift-JIS */
-        error_number = utf8toutf16(symbol, source, utfdata, &length);
+        int error_number = utf8toutf16(symbol, source, utfdata, &length);
         if (error_number != 0) {
             return error_number;
         }
@@ -1424,7 +1423,7 @@ int qr_code(struct zint_symbol *symbol, const unsigned char source[], size_t len
                 jisdata[i] = utfdata[i];
             } else {
                 j = 0;
-                glyph = 0;
+                int glyph = 0;
                 do {
                     if (sjis_lookup[j * 2] == utfdata[i]) {
                         glyph = sjis_lookup[(j * 2) + 1];
@@ -1636,8 +1635,7 @@ static int micro_qr_intermediate(char binary[], const int jisdata[], const char
     /* Convert input data to an "intermediate stage" where data is binary encoded but
        control information is not */
     int position = 0;
-    int short_data_block_length, i;
-    char data_block;
+    int i;
     char buffer[2];
 
     strcpy(binary, "");
@@ -1654,8 +1652,8 @@ static int micro_qr_intermediate(char binary[], const int jisdata[], const char
             return ZINT_ERROR_TOO_LONG;
         }
 
-        data_block = mode[position];
-        short_data_block_length = 0;
+        char data_block = mode[position];
+        int short_data_block_length = 0;
         do {
             short_data_block_length++;
         } while (((short_data_block_length + position) < length) && (mode[position + short_data_block_length] == data_block));
@@ -1759,14 +1757,14 @@ static int micro_qr_intermediate(char binary[], const int jisdata[], const char
                 i = 0;
                 while (i < short_data_block_length) {
                     int count;
-                    int first = 0, second = 0, prod;
+                    int first = 0, prod;
 
                     first = posn(RHODIUM, (char) jisdata[position + i]);
                     count = 1;
                     prod = first;
 
                     if (i + 1 < short_data_block_length && mode[position + i + 1] == 'A') {
-                        second = posn(RHODIUM, (char) jisdata[position + i + 1]);
+                        int second = posn(RHODIUM, (char) jisdata[position + i + 1]);
                         count = 2;
                         prod = (first * 45) + second;
                     }
@@ -1807,20 +1805,20 @@ static int micro_qr_intermediate(char binary[], const int jisdata[], const char
                 i = 0;
                 while (i < short_data_block_length) {
                     int count;
-                    int first = 0, second = 0, third = 0, prod;
+                    int first = 0, prod;
 
                     first = posn(NEON, (char) jisdata[position + i]);
                     count = 1;
                     prod = first;
 
                     if (i + 1 < short_data_block_length && mode[position + i + 1] == 'N') {
-                        second = posn(NEON, (char) jisdata[position + i + 1]);
+                        int second = posn(NEON, (char) jisdata[position + i + 1]);
                         count = 2;
                         prod = (prod * 10) + second;
                     }
 
                     if (i + 2 < short_data_block_length && mode[position + i + 2] == 'N') {
-                        third = posn(NEON, (char) jisdata[position + i + 2]);
+                        int third = posn(NEON, (char) jisdata[position + i + 2]);
                         count = 3;
                         prod = (prod * 10) + third;
                     }
@@ -1985,7 +1983,7 @@ static void microqr_expand_binary(const char binary_stream[], char full_stream[]
 
 static void micro_qr_m1(char binary_data[]) {
     int i, j, latch;
-    int bits_total, bits_left, remainder;
+    int bits_total, bits_left;
     int data_codewords, ecc_codewords;
     unsigned char data_blocks[4], ecc_blocks[3];
 
@@ -2016,7 +2014,7 @@ static void micro_qr_m1(char binary_data[]) {
 
     if (latch == 0) {
         /* Complete current byte */
-        remainder = 8 - (strlen(binary_data) % 8);
+        int remainder = 8 - (strlen(binary_data) % 8);
         if (remainder == 8) {
             remainder = 0;
         }
@@ -2029,7 +2027,7 @@ static void micro_qr_m1(char binary_data[]) {
         if (bits_left > 4) {
             remainder = (bits_left - 4) / 8;
             for (i = 0; i < remainder; i++) {
-                strcat(binary_data, i & 1 ? "00010001" : "11101100");
+                strcat(binary_data, (i & 1) ? "00010001" : "11101100");
             }
         }
         bin_append(0, 4, binary_data);
@@ -2068,7 +2066,7 @@ static void micro_qr_m1(char binary_data[]) {
 
 static void micro_qr_m2(char binary_data[],const int ecc_mode) {
     int i, j, latch;
-    int bits_total=0, bits_left, remainder;
+    int bits_total=0, bits_left;
     int data_codewords=0, ecc_codewords=0;
     unsigned char data_blocks[6], ecc_blocks[7];
 
@@ -2095,7 +2093,7 @@ static void micro_qr_m2(char binary_data[],const int ecc_mode) {
 
     if (latch == 0) {
         /* Complete current byte */
-        remainder = 8 - (strlen(binary_data) % 8);
+        int remainder = 8 - (strlen(binary_data) % 8);
         if (remainder == 8) {
             remainder = 0;
         }
@@ -2107,7 +2105,7 @@ static void micro_qr_m2(char binary_data[],const int ecc_mode) {
         bits_left = bits_total - (int)strlen(binary_data);
         remainder = bits_left / 8;
         for (i = 0; i < remainder; i++) {
-            strcat(binary_data, i & 1 ? "00010001" : "11101100");
+            strcat(binary_data, (i & 1) ? "00010001" : "11101100");
         }
     }
 
@@ -2148,7 +2146,7 @@ static void micro_qr_m2(char binary_data[],const int ecc_mode) {
 
 static void micro_qr_m3(char binary_data[],const int ecc_mode) {
     int i, j, latch;
-    int bits_total=0, bits_left, remainder;
+    int bits_total=0, bits_left;
     int data_codewords=0, ecc_codewords=0;
     unsigned char data_blocks[12], ecc_blocks[9];
 
@@ -2186,7 +2184,7 @@ static void micro_qr_m3(char binary_data[],const int ecc_mode) {
 
     if (latch == 0) {
         /* Complete current byte */
-        remainder = 8 - (strlen(binary_data) % 8);
+        int remainder = 8 - (strlen(binary_data) % 8);
         if (remainder == 8) {
             remainder = 0;
         }
@@ -2199,7 +2197,7 @@ static void micro_qr_m3(char binary_data[],const int ecc_mode) {
         if (bits_left > 4) {
             remainder = (bits_left - 4) / 8;
             for (i = 0; i < remainder; i++) {
-                strcat(binary_data, i & 1 ? "00010001" : "11101100");
+                strcat(binary_data, (i & 1) ? "00010001" : "11101100");
             }
         }
         bin_append(0, 4, binary_data);
@@ -2260,7 +2258,7 @@ static void micro_qr_m3(char binary_data[],const int ecc_mode) {
 
 static void micro_qr_m4(char binary_data[],const int ecc_mode) {
     int i, j, latch;
-    int bits_total=0, bits_left, remainder;
+    int bits_total=0, bits_left;
     int data_codewords=0, ecc_codewords=0;
     unsigned char data_blocks[17], ecc_blocks[15];
 
@@ -2290,7 +2288,7 @@ static void micro_qr_m4(char binary_data[],const int ecc_mode) {
 
     if (latch == 0) {
         /* Complete current byte */
-        remainder = 8 - (strlen(binary_data) % 8);
+        int remainder = 8 - (strlen(binary_data) % 8);
         if (remainder == 8) {
             remainder = 0;
         }
@@ -2302,7 +2300,7 @@ static void micro_qr_m4(char binary_data[],const int ecc_mode) {
         bits_left = bits_total - (int)strlen(binary_data);
         remainder = bits_left / 8;
         for (i = 0; i < remainder; i++) {
-            strcat(binary_data, i & 1 ? "00010001" : "11101100");
+            strcat(binary_data, (i & 1) ? "00010001" : "11101100");
         }
     }
 
@@ -2382,13 +2380,13 @@ static void micro_populate_grid(unsigned char* grid,const int size,const char fu
     int direction = 1; /* up */
     int row = 0; /* right hand side */
     size_t n;
-    int    i,x, y;
+    int i, y;
 
     n = strlen(full_stream);
     y = size - 1;
     i = 0;
     do {
-        x = (size - 2) - (row * 2);
+        int x = (size - 2) - (row * 2);
 
         if (!(grid[(y * size) + (x + 1)] & 0xf0)) {
             if (full_stream[i] == '1') {
@@ -2548,10 +2546,10 @@ static int micro_apply_bitmask(unsigned char *grid,const int size) {
 
 int microqr(struct zint_symbol *symbol, const unsigned char source[], size_t length) {
     size_t i;
-    int    j,size;
+    int    j, size;
     char binary_stream[200];
     char full_stream[200];
-    int utfdata[40],glyph;
+    int utfdata[40];
 
     int jisdata[40];
     char mode[40];
@@ -2589,7 +2587,7 @@ int microqr(struct zint_symbol *symbol, const unsigned char source[], size_t len
                 jisdata[i] = utfdata[i];
             } else {
                 j = 0;
-                glyph = 0;
+                int glyph = 0;
                 do {
                     if (sjis_lookup[j * 2] == utfdata[i]) {
                         glyph = sjis_lookup[(j * 2) + 1];
diff --git a/backend/raster.c b/backend/raster.c
index 08bf9a79..d5c0b294 100644
--- a/backend/raster.c
+++ b/backend/raster.c
@@ -264,7 +264,7 @@ void draw_hexagon(char *pixelbuf, int image_width, char *scaled_hexagon, int hex
 
 void draw_letter(char *pixelbuf, unsigned char letter, int xposn, int yposn, int textflags, int image_width, int image_height) {
     /* Put a letter into a position */
-    int skip, x, y, glyph_no, max_x, max_y;
+    int skip;
 
     skip = 0;
 
@@ -281,14 +281,17 @@ void draw_letter(char *pixelbuf, unsigned char letter, int xposn, int yposn, int
     }
 
     if (skip == 0) {
+        int glyph_no;
         if (letter > 128) {
             glyph_no = letter - 66;
         } else {
             glyph_no = letter - 33;
         }
 
+        int x, y;
 
         switch (textflags) {
+            int max_x, max_y;
             case 1: // small font 5x9
                 max_x = 5;
                 max_y = 9;
@@ -407,14 +410,13 @@ void plot_hexline(char *scaled_hexagon, int hexagon_size, float start_x, float s
     /* Draw a straight line from start to end */
     int i;
     float inc_x, inc_y;
-    float this_x, this_y;
     
     inc_x = (end_x - start_x) / hexagon_size;
     inc_y = (end_y - start_y) / hexagon_size;
     
     for (i = 0; i < hexagon_size; i++) {
-        this_x = start_x + ((float)i * inc_x);
-        this_y = start_y + ((float)i * inc_y);
+        float this_x = start_x + ((float)i * inc_x);
+        float this_y = start_y + ((float)i * inc_y);
         if (((this_x >= 0) && (this_x < hexagon_size)) && ((this_y >= 0) && (this_y < hexagon_size))) {
                 scaled_hexagon[(hexagon_size * (int)this_y) + (int)this_x] = '1';
         }
@@ -424,7 +426,6 @@ void plot_hexline(char *scaled_hexagon, int hexagon_size, float start_x, float s
 void plot_hexagon(char *scaled_hexagon, int hexagon_size) {
     /* Create a hexagon shape and fill it */
     int line, i;
-    char ink;
     
     float x_offset[6];
     float y_offset[6];
@@ -461,7 +462,7 @@ void plot_hexagon(char *scaled_hexagon, int hexagon_size) {
     
     /* Fill hexagon */
     for (line = 0; line < hexagon_size; line++) {
-        ink = '0';
+        char ink = '0';
         for (i = 0; i < hexagon_size; i++) {
             if (scaled_hexagon[(hexagon_size * line) + i] == '1') {
                 if (i < (hexagon_size / 2)) {
@@ -480,7 +481,7 @@ void plot_hexagon(char *scaled_hexagon, int hexagon_size) {
 
 int plot_raster_maxicode(struct zint_symbol *symbol, int rotate_angle, int data_type) {
     /* Plot a MaxiCode symbol with hexagons and bullseye */
-    int i, row, column, xposn, yposn;
+    int i, row, column, xposn;
     int image_height, image_width;
     char *pixelbuf;
     int error_number;
@@ -521,7 +522,7 @@ int plot_raster_maxicode(struct zint_symbol *symbol, int rotate_angle, int data_
     draw_bullseye(pixelbuf, image_width, image_height, (2 * xoffset), (2 * yoffset), scaler * 10);
 
     for (row = 0; row < symbol->rows; row++) {
-        yposn = row * 9;
+        int yposn = row * 9;
         for (column = 0; column < symbol->width; column++) {
             xposn = column * 10;
             if (module_is_set(symbol, row, column)) {
@@ -651,7 +652,7 @@ int plot_raster_default(struct zint_symbol *symbol, int rotate_angle, int data_t
     int i, r, textoffset, yoffset, xoffset, latch, image_width, image_height;
     char *pixelbuf;
     int addon_latch = 0, textflags = 0;
-    int this_row, block_width, plot_height, plot_yposn, textpos;
+    int block_width, textpos;
     float row_height, row_posn;
     int error_number;
     int default_text_posn;
@@ -812,16 +813,16 @@ int plot_raster_default(struct zint_symbol *symbol, int rotate_angle, int data_t
 
     /* Plot the body of the symbol to the pixel buffer */
     for (r = 0; r < symbol->rows; r++) {
-        this_row = symbol->rows - r - 1; /* invert r otherwise plots upside down */
+        int this_row = symbol->rows - r - 1; /* invert r otherwise plots upside down */
         row_posn += row_height;
-        plot_yposn = next_yposn;
+        int plot_yposn = next_yposn;
         if (symbol->row_height[this_row] == 0) {
             row_height = large_bar_height;
         } else {
             row_height = symbol->row_height[this_row];
         }
         next_yposn = (int) (row_posn + row_height);
-        plot_height = next_yposn - plot_yposn;
+        int plot_height = next_yposn - plot_yposn;
 
         i = 0;
         if (module_is_set(symbol, this_row, 0)) {
diff --git a/backend/reedsol.c b/backend/reedsol.c
index affe150a..e0d55052 100644
--- a/backend/reedsol.c
+++ b/backend/reedsol.c
@@ -117,11 +117,11 @@ void rs_init_code(const int nsym, int index) {
 }
 
 void rs_encode(const size_t len,const unsigned char *data, unsigned char *res) {
-    int i, k, m;
+    int i, k;
     for (i = 0; i < rlen; i++)
         res[i] = 0;
     for (i = 0; i < len; i++) {
-        m = res[rlen - 1] ^ data[i];
+        int m = res[rlen - 1] ^ data[i];
         for (k = rlen - 1; k > 0; k--) {
             if (m && rspoly[k])
                 res[k] = (unsigned char) (res[k - 1] ^ alog[(logt[m] + logt[rspoly[k]]) % logmod]);
@@ -137,11 +137,11 @@ void rs_encode(const size_t len,const unsigned char *data, unsigned char *res) {
 
 /* The same as above but for larger bitlengths - Aztec code compatible */
 void rs_encode_long(const int len, const unsigned int *data, unsigned int *res) {
-    int i, k, m;
+    int i, k;
     for (i = 0; i < rlen; i++)
         res[i] = 0;
     for (i = 0; i < len; i++) {
-        m = res[rlen - 1] ^ data[i];
+        int m = res[rlen - 1] ^ data[i];
         for (k = rlen - 1; k > 0; k--) {
             if (m && rspoly[k])
                 res[k] = res[k - 1] ^ alog[(logt[m] + logt[rspoly[k]]) % logmod];
diff --git a/backend/render.c b/backend/render.c
index 9f56b2a9..066fc98d 100644
--- a/backend/render.c
+++ b/backend/render.c
@@ -52,7 +52,7 @@ int render_plot_add_line(struct zint_symbol *symbol, struct zint_render_line *li
 struct zint_render_ring *render_plot_create_ring(float x, float y, float radius, float line_width);
 int render_plot_add_ring(struct zint_symbol *symbol, struct zint_render_ring *ring, struct zint_render_ring **last_ring);
 struct zint_render_hexagon *render_plot_create_hexagon(float x, float y);
-int render_plot_add_hexagon(struct zint_symbol *symbol, struct zint_render_hexagon *ring, struct zint_render_hexagon **last_hexagon);
+int render_plot_add_hexagon(struct zint_symbol *symbol, struct zint_render_hexagon *hexagon, struct zint_render_hexagon **last_hexagon);
 
 int render_plot_add_string(struct zint_symbol *symbol, unsigned char *text, float x, float y, float fsize, float width, struct zint_render_string **last_string);
 
@@ -60,21 +60,20 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
     struct zint_render *render;
     struct zint_render_line *line, *last_line = NULL;
     struct zint_render_string *last_string = NULL;
-    struct zint_render_ring *ring, *last_ring = NULL;
-    struct zint_render_hexagon *hexagon, *last_hexagon = NULL;
+    struct zint_render_ring *last_ring = NULL;
+    struct zint_render_hexagon *last_hexagon = NULL;
 
-    int i, r, block_width, latch, this_row;
-    float textpos, textwidth, large_bar_height, preset_height, row_height, row_posn = 0.0;
+    int i, r, latch;
+    float textpos, large_bar_height, preset_height, row_height, row_posn = 0.0;
     // int error_number = 0;
     int text_offset, text_height, xoffset, yoffset, textdone, main_symbol_width_x, addon_width_x;
-    char addon[6], textpart[10];
+    char addon[6];
     int large_bar_count, symbol_lead_in, total_symbol_width_x, total_area_width_x;
     float addon_text_posn;
     float default_text_posn;
     float scaler;
     const char *locale = NULL;
     int hide_text = 0;
-    float required_aspect;
     float symbol_aspect = 1;
     float x_dimension;
     int upceanflag = 0;
@@ -225,7 +224,7 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
     }
 
     if (large_bar_count == 0) {
-        required_aspect = width / height;
+        float required_aspect = width / height;
         symbol_aspect = (total_symbol_width_x + (2 * xoffset)) / (preset_height + (2 * yoffset) + text_offset + text_height);
         symbol->height = (int) preset_height;
         if (required_aspect > symbol_aspect) {
@@ -337,6 +336,7 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
         render->height = 26.86 * scaler;
 
         /* Central bullseye pattern */
+        struct zint_render_ring *ring;
         ring = render_plot_create_ring(13.64 * scaler, 13.43 * scaler, 0.85 * scaler, 0.67 * scaler);
         render_plot_add_ring(symbol, ring, &last_ring);
         ring = render_plot_create_ring(13.64 * scaler, 13.43 * scaler, 2.20 * scaler, 0.67 * scaler);
@@ -348,7 +348,7 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
         for (r = 0; r < symbol->rows; r++) {
             for (i = 0; i < symbol->width; i++) {
                 if (module_is_set(symbol, r, i)) {
-                    hexagon = render_plot_create_hexagon(((i * 0.88) + (r & 1 ? 1.76 : 1.32)) * scaler, ((r * 0.76) + 0.76) * scaler);
+                    struct zint_render_hexagon *hexagon = render_plot_create_hexagon(((i * 0.88) + ((r & 1) ? 1.76 : 1.32)) * scaler, ((r * 0.76) + 0.76) * scaler);
                     render_plot_add_hexagon(symbol, hexagon, &last_hexagon);
                 }
             }
@@ -360,7 +360,7 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
         int addon_latch = 0;
 
         for (r = 0; r < symbol->rows; r++) {
-            this_row = r;
+            int this_row = r;
             if (symbol->row_height[this_row] == 0) {
                 row_height = large_bar_height;
             } else {
@@ -384,7 +384,7 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
             }
 
             do {
-                block_width = 0;
+                int block_width = 0;
                 do {
                     block_width++;
                 } while (module_is_set(symbol, this_row, i + block_width) == module_is_set(symbol, this_row, i));
@@ -419,6 +419,8 @@ int render_plot(struct zint_symbol *symbol, const float width, const float heigh
     row_posn = (row_posn + large_bar_height) * scaler;
 
     if (!hide_text) {
+        char textpart[10];
+        float textwidth;
         if (upceanflag == 8) {
             /* guard bar extensions and text formatting for EAN-8 */
             i = 0;
diff --git a/backend/rss.c b/backend/rss.c
index c34b615c..2e7a5a9f 100644
--- a/backend/rss.c
+++ b/backend/rss.c
@@ -164,8 +164,8 @@ int rss14(struct zint_symbol *symbol, unsigned char source[], int src_len) {
     short int accum[112], left_reg[112], right_reg[112], x_reg[112], y_reg[112];
     int data_character[4], data_group[4], v_odd[4], v_even[4];
     int data_widths[8][4], checksum, c_left, c_right, total_widths[46], writer;
-    char latch, hrt[15], temp[32];
-    int check_digit, count, separator_row;
+    char latch, temp[32];
+    int separator_row;
 
     separator_row = 0;
 
@@ -486,8 +486,9 @@ int rss14(struct zint_symbol *symbol, unsigned char source[], int src_len) {
         }
         symbol->rows = symbol->rows + 1;
 
-        count = 0;
-        check_digit = 0;
+        int count = 0;
+        int check_digit = 0;
+        char hrt[15];
 
         /* Calculate check digit from Annex A and place human readable text */
         ustrcpy(symbol->text, (unsigned char*) "(01)");
@@ -1054,10 +1055,10 @@ int rsslimited(struct zint_symbol *symbol, unsigned char source[], int src_len)
 
 /* Attempts to apply encoding rules from secions 7.2.5.5.1 to 7.2.5.5.3
  * of ISO/IEC 24724:2006 */
-int general_rules(char field[], char type[]) {
+int general_rules(char type[]) {
 
     int block[2][200], block_count, i, j, k;
-    char current, next, last;
+    char current;
 
     block_count = 0;
 
@@ -1066,7 +1067,7 @@ int general_rules(char field[], char type[]) {
 
     for (i = 1; i < strlen(type); i++) {
         current = type[i];
-        last = type[i - 1];
+        char last = type[i - 1];
 
         if (current == last) {
             block[0][block_count] = block[0][block_count] + 1;
@@ -1081,7 +1082,7 @@ int general_rules(char field[], char type[]) {
 
     for (i = 0; i < block_count; i++) {
         current = block[1][i];
-        next = (block[1][i + 1] & 0xFF);
+        char next = (block[1][i + 1] & 0xFF);
 
         if ((current == ISOIEC) && (i != (block_count - 1))) {
             if ((next == ANY_ENC) && (block[0][i + 1] >= 4)) {
@@ -1205,7 +1206,6 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
             if (source[18] == '0') {
                 /* (01) and (310x) */
                 char weight_str[7];
-                float weight; /* In kilos */
 
                 for (i = 0; i < 6; i++) {
                     weight_str[i] = source[20 + i];
@@ -1219,6 +1219,7 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
 
                     if ((source[19] == '3') && (strlen(source) == 26)) {
                         /* (01) and (3103) */
+                        float weight; /* In kilos */
                         weight = atof(weight_str) / 1000.0;
 
                         if (weight <= 32.767) {
@@ -1258,7 +1259,6 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
             if (source[18] == '0') {
                 /* (01) and (320x) */
                 char weight_str[7];
-                float weight; /* In pounds */
 
                 for (i = 0; i < 6; i++) {
                     weight_str[i] = source[20 + i];
@@ -1271,6 +1271,7 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
 
                     if (((source[19] == '2') || (source[19] == '3')) && (strlen(source) == 26)) {
                         /* (01) and (3202)/(3203) */
+                        float weight; /* In pounds */
 
                         if (source[19] == '3') {
                             weight = (float) (atof(weight_str) / 1000.0F);
@@ -1454,7 +1455,6 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
         char group[4];
         int group_val;
         char weight_str[8];
-        char date_str[4];
 
         for (i = 1; i < 5; i++) {
             group[0] = source[(i * 3)];
@@ -1476,6 +1476,7 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
 
         if (strlen(source) == 34) {
             /* Date information is included */
+            char date_str[4];
             date_str[0] = source[28];
             date_str[1] = source[29];
             date_str[2] = '\0';
@@ -1592,7 +1593,7 @@ int rss_binary_string(struct zint_symbol *symbol, char source[], char binary_str
         }
     }
 
-    latch = general_rules(general_field, general_field_type);
+    latch = general_rules(general_field_type);
     if (debug) printf("General field type: %s\n", general_field_type);
 
     last_mode = NUMERIC;
@@ -1863,8 +1864,6 @@ int rssexpanded(struct zint_symbol *symbol, unsigned char source[], int src_len)
     char substring[21][14], latch;
     int char_widths[21][8], checksum, check_widths[8], c_group;
     int check_char, c_odd, c_even, elements[235], pattern_width, reader, writer;
-    int row, elements_in_sub, special_case_row, left_to_right;
-    int codeblocks, sub_elements[235], stack_rows, current_row, current_block;
     int separator_row;
 #ifndef _MSC_VER
     char reduced[src_len + 1], binary_string[(7 * src_len) + 1];
@@ -1958,7 +1957,7 @@ int rssexpanded(struct zint_symbol *symbol, unsigned char source[], int src_len)
        elements in the data characters. */
     checksum = 0;
     for (i = 0; i < data_chars; i++) {
-        row = weight_rows[(((data_chars - 2) / 2) * 21) + i];
+        int row = weight_rows[(((data_chars - 2) / 2) * 21) + i];
         for (j = 0; j < 8; j++) {
             checksum += (char_widths[i][j] * checksum_weight_exp[(row * 8) + j]);
 
@@ -2102,7 +2101,7 @@ int rssexpanded(struct zint_symbol *symbol, unsigned char source[], int src_len)
          * [01]90614141999996[10]1234222222222221
          * Patch by Daniel Frede
          */
-        codeblocks = (data_chars + 1) / 2 + ((data_chars + 1) % 2);
+        int codeblocks = (data_chars + 1) / 2 + ((data_chars + 1) % 2);
 
 
         if ((symbol->option_2 < 1) || (symbol->option_2 > 10)) {
@@ -2115,22 +2114,23 @@ int rssexpanded(struct zint_symbol *symbol, unsigned char source[], int src_len)
             symbol->option_2 = 2;
         }
 
-        stack_rows = codeblocks / symbol->option_2;
+        int stack_rows = codeblocks / symbol->option_2;
         if (codeblocks % symbol->option_2 > 0) {
             stack_rows++;
         }
 
-        current_block = 0;
+        int current_row, current_block = 0, left_to_right;
         for (current_row = 1; current_row <= stack_rows; current_row++) {
+            int sub_elements[235];
             for (i = 0; i < 235; i++) {
                 sub_elements[i] = 0;
             }
-            special_case_row = 0;
+            int special_case_row = 0;
 
             /* Row Start */
             sub_elements[0] = 1; // left guard
             sub_elements[1] = 1;
-            elements_in_sub = 2;
+            int elements_in_sub = 2;
 
             /* Row Data */
             reader = 0;
@@ -2139,7 +2139,7 @@ int rssexpanded(struct zint_symbol *symbol, unsigned char source[], int src_len)
                         ((current_row == stack_rows) && (codeblocks != (current_row * symbol->option_2)) &&
                         (((current_row * symbol->option_2) - codeblocks) & 1))) {
                     /* left to right */
-                    left_to_right = 1;
+                     left_to_right = 1;
                     i = 2 + (current_block * 21);
                     for (j = 0; j < 21; j++) {
                         if ((i + j) < pattern_width) {
@@ -2167,7 +2167,7 @@ int rssexpanded(struct zint_symbol *symbol, unsigned char source[], int src_len)
             sub_elements[elements_in_sub + 1] = 1;
             elements_in_sub += 2;
 
-            latch = current_row & 1 ? '0' : '1';
+            latch = (current_row & 1) ? '0' : '1';
 
             if ((current_row == stack_rows) && (codeblocks != (current_row * symbol->option_2)) &&
                     ((current_row & 1) == 0) && ((symbol->option_2 & 1) == 0)) {
diff --git a/backend/svg.c b/backend/svg.c
index 04a1ab66..a36584b1 100644
--- a/backend/svg.c
+++ b/backend/svg.c
@@ -44,7 +44,7 @@
 #define SSET	"0123456789ABCDEF"
 
 int svg_plot(struct zint_symbol *symbol) {
-    int i, block_width, latch, r, this_row;
+    int i, block_width, latch, r;
     float textpos, large_bar_height, preset_height, row_height, row_posn = 0.0;
     FILE *fsvg;
     int error_number = 0;
@@ -306,7 +306,7 @@ int svg_plot(struct zint_symbol *symbol) {
         int addon_latch = 0;
 
         for (r = 0; r < symbol->rows; r++) {
-            this_row = r;
+            int this_row = r;
             if (symbol->row_height[this_row] == 0) {
                 row_height = large_bar_height;
             } else {
diff --git a/backend/tif.c b/backend/tif.c
index 7b9b3608..901b47c8 100644
--- a/backend/tif.c
+++ b/backend/tif.c
@@ -232,7 +232,7 @@ int tif_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
     ifd.y_resolution.type = 5;
     ifd.y_resolution.count = 1;
     ifd.y_resolution.offset = free_memory;
-    free_memory += 8;
+//    free_memory += 8;
     
     ifd.planar_config.tag = 0x11c;
     ifd.planar_config.type = 3;
diff --git a/backend/zint.h b/backend/zint.h
index 988db7d0..534575c1 100644
--- a/backend/zint.h
+++ b/backend/zint.h
@@ -261,7 +261,7 @@ extern "C" {
     ZINT_EXTERN void ZBarcode_Clear(struct zint_symbol *symbol);
     ZINT_EXTERN void ZBarcode_Delete(struct zint_symbol *symbol);
 
-    ZINT_EXTERN int ZBarcode_Encode(struct zint_symbol *symbol, const unsigned char *input, int length);
+    ZINT_EXTERN int ZBarcode_Encode(struct zint_symbol *symbol, const unsigned char *source, int in_length);
     ZINT_EXTERN int ZBarcode_Encode_File(struct zint_symbol *symbol, char *filename);
     ZINT_EXTERN int ZBarcode_Print(struct zint_symbol *symbol, int rotate_angle);
     ZINT_EXTERN int ZBarcode_Encode_and_Print(struct zint_symbol *symbol, unsigned char *input, int length, int rotate_angle);
diff --git a/backend_qt/qzint.cpp b/backend_qt/qzint.cpp
index ba5815fa..3a472d9f 100644
--- a/backend_qt/qzint.cpp
+++ b/backend_qt/qzint.cpp
@@ -100,7 +100,7 @@ namespace Zint {
         m_whitespace = m_zintSymbol->whitespace_width;
     }
 
-    int QZint::symbol() {
+    int QZint::symbol() const {
         return m_symbol;
     }
 
@@ -112,7 +112,7 @@ namespace Zint {
         m_input_mode = input_mode;
     }
 
-    QString QZint::text() {
+    QString QZint::text() const {
         return m_text;
     }
 
@@ -125,7 +125,7 @@ namespace Zint {
         target_size_vert = height;
     }
 
-    QString QZint::primaryMessage() {
+    QString QZint::primaryMessage() const {
         return m_primaryMessage;
     }
 
@@ -135,7 +135,7 @@ namespace Zint {
 
     int QZint::height() {
         encode();
-        return (m_zintSymbol->height + (m_border != NO_BORDER) ? m_borderWidth * 2 : 0)*(m_zintSymbol->symbology == BARCODE_MAXICODE ? (maxi_width + 1) : 1);
+        return (m_zintSymbol->height + (m_border != NO_BORDER ? m_borderWidth * 2 : 0)*(m_zintSymbol->symbology == BARCODE_MAXICODE ? (maxi_width + 1) : 1));
     }
 
     void QZint::setHeight(int height) {
@@ -152,10 +152,10 @@ namespace Zint {
 
     int QZint::width() {
         encode();
-        return (m_zintSymbol->width + (m_border == BOX) ? m_borderWidth * 2 : 0)*(m_zintSymbol->symbology == BARCODE_MAXICODE ? (maxi_width + 1) : 1);
+        return (m_zintSymbol->width + (m_border == BOX ? m_borderWidth * 2 : 0)*(m_zintSymbol->symbology == BARCODE_MAXICODE ? (maxi_width + 1) : 1));
     }
 
-    float QZint::scale() {
+    float QZint::scale() const {
         return m_scale;
     }
 
@@ -167,7 +167,7 @@ namespace Zint {
         m_dot_size = dot_size;
     }
 
-    QColor QZint::fgColor() {
+    QColor QZint::fgColor() const {
         return m_fgColor;
     }
 
@@ -175,7 +175,7 @@ namespace Zint {
         m_fgColor = fgColor;
     }
 
-    QColor QZint::bgColor() {
+    QColor QZint::bgColor() const {
         return m_bgColor;
     }
 
@@ -183,7 +183,7 @@ namespace Zint {
         m_bgColor = bgColor;
     }
 
-    QZint::BorderType QZint::borderType() {
+    QZint::BorderType QZint::borderType() const {
         return m_border;
     }
 
@@ -191,7 +191,7 @@ namespace Zint {
         m_border = border;
     }
 
-    int QZint::borderWidth() {
+    int QZint::borderWidth() const {
         return m_borderWidth;
     }
 
@@ -205,7 +205,7 @@ namespace Zint {
         m_whitespace = whitespace;
     }
 
-    int QZint::pdf417CodeWords() {
+    int QZint::pdf417CodeWords() const {
         return m_pdf417CodeWords;
     }
 
@@ -213,7 +213,7 @@ namespace Zint {
         m_pdf417CodeWords = pdf417CodeWords;
     }
 
-    int QZint::securityLevel() {
+    int QZint::securityLevel() const {
         return m_securityLevel;
     }
 
@@ -221,11 +221,11 @@ namespace Zint {
         m_securityLevel = securityLevel;
     }
 
-    QString QZint::error_message() {
+    QString QZint::error_message() const {
         return m_lastError;
     }
 
-    int QZint::mode() {
+    int QZint::mode() const {
         return m_securityLevel;
     }
 
@@ -286,7 +286,7 @@ namespace Zint {
         }
     }
 
-    int QZint::module_set(int y_coord, int x_coord) {
+    int QZint::module_set(int y_coord, int x_coord) const {
         int x_char, x_sub, result;
 
         x_char = x_coord / 7;
@@ -304,7 +304,7 @@ namespace Zint {
         bool textdone;
         int comp_offset = 0;
         int xoffset = m_whitespace;
-        int j, main_width = 0, addon_text_height = 0;
+        int main_width = 0, addon_text_height = 0;
         int yoffset = 0;
         
         encode();
@@ -602,7 +602,7 @@ namespace Zint {
                 int block_width;
                 bool latch = true;
 
-                j = 0 + comp_offset;
+                int j = 0 + comp_offset;
                 do {
                     block_width = 0;
                     do {
@@ -681,7 +681,7 @@ namespace Zint {
         painter.restore();
     }
 
-    const QString & QZint::lastError() {
+    const QString & QZint::lastError() const {
         return m_lastError;
     }
 
diff --git a/backend_qt/qzint.h b/backend_qt/qzint.h
index c3192250..85bfbd1c 100644
--- a/backend_qt/qzint.h
+++ b/backend_qt/qzint.h
@@ -36,13 +36,13 @@ public:
 	QZint();
 	~QZint();
 
-	int  symbol();
+    int  symbol() const;
 	void setSymbol(int symbol);
 
-	QString text();
+    QString text() const;
 	void setText(const QString & text);
 
-	QString primaryMessage();
+    QString primaryMessage() const;
 	void setPrimaryMessage(const QString & primaryMessage);
 
 	void setHeight(int height);
@@ -53,41 +53,41 @@ public:
 	
 	void setOption3(int option);
 
-	QColor fgColor();
+    QColor fgColor() const;
 	void setFgColor(const QColor & fgColor);
 
-	QColor bgColor();
+    QColor bgColor() const;
 	void setBgColor(const QColor & bgColor);
 
-	BorderType borderType();
+    BorderType borderType() const;
 	void setBorderType(BorderType border);
 
-	int borderWidth();
+    int borderWidth() const;
 	void setBorderWidth(int boderWidth);
 
-	int pdf417CodeWords();
+    int pdf417CodeWords() const;
 	void setPdf417CodeWords(int pdf417CodeWords);
 
-	int securityLevel();
+    int securityLevel() const;
 	void setSecurityLevel(int securityLevel);
 
-	float scale();
+    float scale() const;
 	void setScale(float scale);
         
         void setDotSize(float dot_size);
 
-	int mode();
+    int mode() const;
 	void setMode(int securityLevel);
 
 	void setInputMode(int input_mode);
 
 	void setWhitespace(int whitespace);
 
-	QString error_message();
+    QString error_message() const;
 
 	void render(QPainter & painter, const QRectF & paintRect, AspectRatioMode mode=IgnoreAspectRatio);
 
-	const QString & lastError();
+    const QString & lastError() const;
 	bool hasErrors();
 
 	bool save_to_file(QString filename);
@@ -98,7 +98,7 @@ public:
 
 private:
 	void encode();
-	int module_set(int y_coord, int x_coord);
+    int module_set(int y_coord, int x_coord) const;
 
 private:
 	int m_symbol;
@@ -120,9 +120,9 @@ private:
 	float m_scale;
 	int m_option_3;
 	bool m_hidetext;
-        float m_dot_size;
-        int target_size_horiz;
-        int target_size_vert;
+    float m_dot_size;
+    int target_size_horiz;
+    int target_size_vert;
 };
 }
 #endif
diff --git a/backend_tcl/zint.c b/backend_tcl/zint.c
index 66d0d301..7be03b55 100644
--- a/backend_tcl/zint.c
+++ b/backend_tcl/zint.c
@@ -330,7 +330,7 @@ EXPORT BOOL WINAPI DllEntryPoint (HINSTANCE hInstance,
 #endif
 /*----------------------------------------------------------------------------*/
 /* Initialisation Procedures */
-EXPORT int Zint_Init (Tcl_Interp *Interp)
+EXPORT int Zint_Init (Tcl_Interp *interp)
 {
     /*------------------------------------------------------------------------*/
 #ifdef USE_TCL_STUBS
@@ -365,7 +365,6 @@ static int Zint(ClientData unused, Tcl_Interp *interp, int objc,
     Tcl_Obj *CONST objv[])
 {
     /* Option list and indexes */
-    char *subCmds[] = {"encode", "symbologies", "version", "help", NULL};
     enum iCommand {iEncode, iSymbologies, iVersion, iHelp};
     /* choice of option */
     int Index;
@@ -373,6 +372,7 @@ static int Zint(ClientData unused, Tcl_Interp *interp, int objc,
     /* > Check if option argument is given and decode it */
     if (objc > 1)
     {
+    char *subCmds[] = {"encode", "symbologies", "version", "help", NULL};
         if(Tcl_GetIndexFromObj(interp, objv[1], (const char **) subCmds,
             "option", 0, &Index)
             == TCL_ERROR)
diff --git a/frontend/getopt.c b/frontend/getopt.c
index b270074b..cda551f2 100644
--- a/frontend/getopt.c
+++ b/frontend/getopt.c
@@ -1150,14 +1150,13 @@ getopt (int argc, char *const *argv, const char *optstring)
 int
 main (int argc, char **argv)
 {
-  int c;
   int digit_optind = 0;
 
   while (1)
     {
       int this_option_optind = optind ? optind : 1;
 
-      c = getopt (argc, argv, "abc:d:0123456789");
+      int c = getopt (argc, argv, "abc:d:0123456789");
       if (c == -1)
 	break;
 
diff --git a/frontend/getopt1.c b/frontend/getopt1.c
index e3624625..3da3cd80 100644
--- a/frontend/getopt1.c
+++ b/frontend/getopt1.c
@@ -99,7 +99,6 @@ libc_hidden_def (getopt_long_only)
 int
 main (int argc, char **argv)
 {
-  int c;
   int digit_optind = 0;
 
   while (1)
@@ -117,7 +116,7 @@ main (int argc, char **argv)
 	{0, 0, 0, 0}
       };
 
-      c = getopt_long (argc, argv, "abc:d:0123456789",
+      int c = getopt_long (argc, argv, "abc:d:0123456789",
 		       long_options, &option_index);
       if (c == -1)
 	break;
diff --git a/frontend/main.c b/frontend/main.c
index be9fea8a..59b3e2dc 100644
--- a/frontend/main.c
+++ b/frontend/main.c
@@ -151,10 +151,10 @@ void show_eci(void) {
 
 /* Verifies that a string only uses valid characters */
 int validator(char test_string[], char source[]) {
-    unsigned int i, j, latch;
+    unsigned int i, j;
 
     for (i = 0; i < strlen(source); i++) {
-        latch = 0;
+        unsigned int latch = 0;
         for (j = 0; j < strlen(test_string); j++) {
             if (source[i] == test_string[j]) {
                 latch = 1;
@@ -434,7 +434,6 @@ int batch_process(struct zint_symbol *symbol, char *filename, int mirror_mode, c
 
 int main(int argc, char **argv) {
     struct zint_symbol *my_symbol;
-    int c;
     int error_number;
     int rotate_angle;
     int generated;
@@ -504,7 +503,7 @@ int main(int argc, char **argv) {
             {"verbose", 0, 0, 0}, // Currently undocumented, output some debug info
             {0, 0, 0, 0}
         };
-        c = getopt_long(argc, argv, "htb:w:d:o:i:rcmpe", long_options, &option_index);
+        int c = getopt_long(argc, argv, "htb:w:d:o:i:rcmpe", long_options, &option_index);
         if (c == -1) break;
 
         switch (c) {
diff --git a/frontend_qt/datawindow.cpp b/frontend_qt/datawindow.cpp
index 9478a145..c62199d7 100644
--- a/frontend_qt/datawindow.cpp
+++ b/frontend_qt/datawindow.cpp
@@ -36,7 +36,7 @@ DataWindow::DataWindow()
 	connect(btnOK, SIGNAL( clicked( bool )), SLOT(okay()));
 }
 
-DataWindow::DataWindow(QString input)
+DataWindow::DataWindow(const QString &input)
 {
 	setupUi(this);
 	txtDataInput->setPlainText(input);
diff --git a/frontend_qt/datawindow.h b/frontend_qt/datawindow.h
index d5d45d89..6834d834 100644
--- a/frontend_qt/datawindow.h
+++ b/frontend_qt/datawindow.h
@@ -28,7 +28,7 @@ class DataWindow : public QDialog, private Ui::DataDialog
 
 public:
 	DataWindow();
-	DataWindow(QString input);
+    explicit DataWindow(const QString &input);
 	~DataWindow();
 	int Valid;
 	QString DataOutput;
diff --git a/frontend_qt/exportwindow.cpp b/frontend_qt/exportwindow.cpp
index 6fe40ee1..3956e26f 100644
--- a/frontend_qt/exportwindow.cpp
+++ b/frontend_qt/exportwindow.cpp
@@ -81,7 +81,7 @@ void ExportWindow::process()
 	QString dataString;
 	QString suffix;
         QString Feedback;
-	int lines, i, j, inputpos, datalen;
+    int lines, i, j, inputpos;
 	
 	lines = output_data.count(QChar('\n'), Qt::CaseInsensitive);
 	inputpos = 0;
@@ -110,7 +110,7 @@ void ExportWindow::process()
         Feedback = "";
         
 	for(i = 0; i < lines; i++) {
-		datalen = 0;
+        int datalen = 0;
 		for(j = inputpos; ((j < output_data.length()) && (output_data[j] != '\n') ); j++) {
 			datalen++;
 		}
@@ -119,12 +119,11 @@ void ExportWindow::process()
 			case 0: { /* Same as Data (URL Escaped) */
 					QString url_escaped;
 					int m;
-					char name_char;
 					QChar name_qchar;
 					
 					for(m = 0; m < dataString.length(); m++) {
 						name_qchar = dataString[m];
-						name_char = name_qchar.toLatin1();
+                        char name_char = name_qchar.toLatin1();
 						
 						switch(name_char) {
 							case '\\': url_escaped += "%5C"; break;
diff --git a/frontend_qt/sequencewindow.cpp b/frontend_qt/sequencewindow.cpp
index 09b685ba..4789cfa9 100644
--- a/frontend_qt/sequencewindow.cpp
+++ b/frontend_qt/sequencewindow.cpp
@@ -75,7 +75,6 @@ QString SequenceWindow::apply_format(QString raw_number)
 	QString adjusted, reversed;
 	QString format;
 	int format_len, input_len, i, inpos;
-	char format_char;
 	QChar format_qchar;
 	
 	format = linFormat->text();
@@ -86,7 +85,7 @@ QString SequenceWindow::apply_format(QString raw_number)
 	
 	for(i = format_len; i > 0; i--) {
 		format_qchar = format[i - 1];
-		format_char = format_qchar.toLatin1();
+        char format_char = format_qchar.toLatin1();
 		switch(format_char) {
 			case '#':
 				if (inpos > 0) {