diff --git a/backend/aztec.c b/backend/aztec.c
index 891f9ee9..ed086b96 100644
--- a/backend/aztec.c
+++ b/backend/aztec.c
@@ -65,7 +65,7 @@ void insert(char binary_string[], int posn, char newbit) {
  * Encode input data into a binary string
  */
 int aztec_text_process(unsigned char source[], const unsigned int src_len, char binary_string[], int gs1) {
-    int i, j, k, bytes;
+    int i, j, k, p, bytes;
     int curtable, newtable, lasttable, chartype, maplength, blocks, debug;
 #ifndef _MSC_VER
     int charmap[src_len * 2], typemap[src_len * 2];
@@ -630,7 +630,7 @@ int aztec_text_process(unsigned char source[], const unsigned int src_len, char
                             /* Put 00000 followed by 11-bit number of bytes less 31 */
                             concat(binary_string, "00000");
                             
-                            for (int p = 0; p < 11; p++) {
+                            for (p = 0; p < 11; p++) {
                                 if ((bytes - 31) & (0x400 >> p)) {
                                     concat(binary_string, "1");
                                 } else {
@@ -639,7 +639,7 @@ int aztec_text_process(unsigned char source[], const unsigned int src_len, char
                             }
                         } else {
                             /* Put 5-bit number of bytes */
-                            for (int p = 0; p < 5; p++) {
+                            for (p = 0; p < 5; p++) {
                                 if (bytes & (0x10 >> p)) {
                                     concat(binary_string, "1");
                                 } else {
@@ -678,7 +678,7 @@ int aztec_text_process(unsigned char source[], const unsigned int src_len, char
                 if (debug) printf("%d ", charmap[i]);
                 break;
             case BINARY:
-                for (int p = 0; p < 8; p++) {
+                for (p = 0; p < 8; p++) {
                     if (charmap[i] & (0x80 >> p)) {
                         concat(binary_string, "1");
                     } else {
@@ -856,7 +856,7 @@ void popilate_map() {
 }
 
 int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
-    int x, y, i, j, data_blocks, ecc_blocks, layers, total_bits;
+    int x, y, i, j, p, data_blocks, ecc_blocks, layers, total_bits;
     char binary_string[20000], bit_pattern[20045], descriptor[42];
     char adjusted_string[20000];
     unsigned char desc_data[4], desc_ecc[6];
@@ -1255,7 +1255,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
     switch (codeword_size) {
         case 6:
             for (i = 0; i < data_blocks; i++) {
-                for (int p = 0; p < 6; p++) {
+                for (p = 0; p < 6; p++) {
                     if (adjusted_string[i * codeword_size + p] == '1') {
                         data_part[i] += (0x20 >> p);
                     }
@@ -1265,7 +1265,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
             rs_init_code(ecc_blocks, 1);
             rs_encode_long(data_blocks, data_part, ecc_part);
             for (i = (ecc_blocks - 1); i >= 0; i--) {
-                for (int p = 0; p < 6; p++) {
+                for (p = 0; p < 6; p++) {
                     if (ecc_part[i] & (0x20 >> p)) {
                         concat(adjusted_string, "1");
                     } else {
@@ -1277,7 +1277,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
             break;
         case 8:
             for (i = 0; i < data_blocks; i++) {
-                for (int p = 0; p < 8; p++) {
+                for (p = 0; p < 8; p++) {
                     if (adjusted_string[i * codeword_size + p] == '1') {
                         data_part[i] += (0x80 >> p);
                     }
@@ -1287,7 +1287,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
             rs_init_code(ecc_blocks, 1);
             rs_encode_long(data_blocks, data_part, ecc_part);
             for (i = (ecc_blocks - 1); i >= 0; i--) {
-                for (int p = 0; p < 8; p++) {
+                for (p = 0; p < 8; p++) {
                     if (ecc_part[i] & (0x80 >> p)) {
                         concat(adjusted_string, "1");
                     } else {
@@ -1309,7 +1309,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
             rs_init_code(ecc_blocks, 1);
             rs_encode_long(data_blocks, data_part, ecc_part);
             for (i = (ecc_blocks - 1); i >= 0; i--) {
-                for (int p = 0; p < 10; p++) {
+                for (p = 0; p < 10; p++) {
                     if (ecc_part[i] & (0x200 >> p)) {
                         concat(adjusted_string, "1");
                     } else {
@@ -1321,7 +1321,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
             break;
         case 12:
             for (i = 0; i < data_blocks; i++) {
-                for (int p = 0; p < 12; p++) {
+                for (p = 0; p < 12; p++) {
                     if (adjusted_string[i * codeword_size + p] == '1') {
                         data_part[i] += (0x800 >> p);
                     }
@@ -1331,7 +1331,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
             rs_init_code(ecc_blocks, 1);
             rs_encode_long(data_blocks, data_part, ecc_part);
             for (i = (ecc_blocks - 1); i >= 0; i--) {
-                for (int p = 0; p < 12; p++) {
+                for (p = 0; p < 12; p++) {
                     if (ecc_part[i] & (0x800 >> p)) {
                         concat(adjusted_string, "1");
                     } else {
@@ -1620,7 +1620,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[], int length) {
 
 /* Encodes Aztec runes as specified in ISO/IEC 24778:2008 Annex A */
 int aztec_runes(struct zint_symbol *symbol, unsigned char source[], int length) {
-    int input_value, error_number, i, y, x;
+    int input_value, error_number, i, p, y, x;
     char binary_string[28];
     unsigned char data_codewords[3], ecc_codewords[6];
 
@@ -1653,7 +1653,7 @@ int aztec_runes(struct zint_symbol *symbol, unsigned char source[], int length)
     }
 
     strcpy(binary_string, "");
-    for (int p = 0; p < 8; p++) {
+    for (p = 0; p < 8; p++) {
         if (input_value & (0x80 >> p)) {
             concat(binary_string, "1");
         } else {
diff --git a/backend/code1.c b/backend/code1.c
index da47fa11..4efcc172 100644
--- a/backend/code1.c
+++ b/backend/code1.c
@@ -355,7 +355,7 @@ int c1_look_ahead_test(unsigned char source[], int sourcelen, int position, int
 
 int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int target[], int length) {
     int current_mode, next_mode;
-    int sp, tp, gs1, i, j, latch;
+    int sp, tp, gs1, i, j, p, latch;
     int c40_buffer[6], c40_p;
     int text_buffer[6], text_p;
     int edi_buffer[6], edi_p;
@@ -1015,7 +1015,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
                 /* There are three digits - convert the value to binary */
                 value = (100 * ctoi(source[sp])) + (10 * ctoi(source[sp + 1])) + ctoi(source[sp + 2]) + 1;
 
-                for (int p = 0; p < 10; p++) {
+                for (p = 0; p < 10; p++) {
                     if (value & (0x200 >> p)) {
                         concat(decimal_binary, "1");
                     } else {
@@ -1032,7 +1032,7 @@ int c1_encode(struct zint_symbol *symbol, unsigned char source[], unsigned int t
 
                 /* Binary buffer is full - transfer to target */
                 
-                for (int p = 0; p < 8; p++) {
+                for (p = 0; p < 8; p++) {
                     if (decimal_binary[p] == '1') {
                         target1 += (0x80 >> p);
                     }
diff --git a/backend/composite.c b/backend/composite.c
index b4585fb0..3886be8e 100644
--- a/backend/composite.c
+++ b/backend/composite.c
@@ -371,7 +371,7 @@ int cc_b(struct zint_symbol *symbol, char source[], int cc_width) {
     unsigned char* data_string = (unsigned char*) _alloca((strlen(source) / 8) + 3);
 #endif
     int chainemc[180], mclength;
-    int k, j, longueur, mccorrection[50], offset;
+    int k, j, p, longueur, mccorrection[50], offset;
     int total, dummy[5];
     char codebarre[100], pattern[580];
     int variant, LeftRAPStart, CentreRAPStart, RightRAPStart, StartCluster;
@@ -383,7 +383,7 @@ int cc_b(struct zint_symbol *symbol, char source[], int cc_width) {
         binloc = i * 8;
 
         data_string[i] = 0;
-        for (int p = 0; p < 8; p++) {
+        for (p = 0; p < 8; p++) {
             if (source[binloc + p] == '1') {
                 data_string[i] += (0x80 >> p);
             }
@@ -647,7 +647,7 @@ int cc_b(struct zint_symbol *symbol, char source[], int cc_width) {
 
 /* CC-C 2D component - byte compressed PDF417 */
 int cc_c(struct zint_symbol *symbol, char source[], int cc_width, int ecc_level) { 
-    int length, i, binloc;
+    int length, i, p, binloc;
 #ifndef _MSC_VER
     unsigned char data_string[(strlen(source) / 8) + 4];
 #else
@@ -664,7 +664,7 @@ int cc_c(struct zint_symbol *symbol, char source[], int cc_width, int ecc_level)
         binloc = i * 8;
 
         data_string[i] = 0;
-        for (int p = 0; p < 8; p++) {
+        for (p = 0; p < 8; p++) {
             if (source[binloc + p] == '1') {
                 data_string[i] += (0x80 >> p);
             }
diff --git a/backend/gridmtx.c b/backend/gridmtx.c
index d872df81..1c26e81d 100644
--- a/backend/gridmtx.c
+++ b/backend/gridmtx.c
@@ -313,7 +313,9 @@ int seek_forward(int gbdata[], int length, int position, int current_mode) {
 
 /* Add the length indicator for byte encoded blocks */
 void add_byte_count(char binary[], int byte_count_posn, int byte_count) {
-    for (int p = 0; p < 8; p++) {
+    int p;
+    
+    for (p = 0; p < 8; p++) {
         if (byte_count & (0x100 >> p)) {
             binary[byte_count_posn + p] = '0';
         } else {
@@ -324,7 +326,7 @@ void add_byte_count(char binary[], int byte_count_posn, int byte_count) {
 
 /* Add a control character to the data stream */
 void add_shift_char(char binary[], int shifty) {
-    int i, debug = 0;
+    int i, p, debug = 0;
     int glyph = 0;
 
     for (i = 0; i < 64; i++) {
@@ -337,7 +339,7 @@ void add_shift_char(char binary[], int shifty) {
         printf("SHIFT [%d] ", glyph);
     }
 
-    for (int p = 0; p < 6; p++) {
+    for (p = 0; p < 6; p++) {
         if (glyph & (0x20 >> p)) {
             concat(binary, "1");
         } else {
@@ -356,7 +358,7 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
     int numbuf[3], punt = 0;
     int number_pad_posn, debug = 0;
     int byte_count_posn = 0, byte_count = 0;
-    int shift, i;
+    int shift, i, q;
 
     strcpy(binary, "");
 
@@ -543,8 +545,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                     printf("[%d] ", glyph);
                 }
 
-                for (int p = 0; p < 13; p++) {
-                    if (glyph & (0x1000 >> p)) {
+                for (q = 0; q < 13; q++) {
+                    if (glyph & (0x1000 >> q)) {
                         concat(binary, "1");
                     } else {
                         concat(binary, "0");
@@ -617,8 +619,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                         printf("[%d] ", glyph);
                     }
 
-                    for (int p = 0; p < 10; p++) {
-                        if (glyph & (0x200 >> p)) {
+                    for (q = 0; q < 10; q++) {
+                        if (glyph & (0x200 >> q)) {
                             concat(binary, "1");
                         } else {
                             concat(binary, "0");
@@ -631,8 +633,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                     printf("[%d] ", glyph);
                 }
 
-                for (int p = 0; p < 10; p++) {
-                    if (glyph & (0x200 >> p)) {
+                for (q = 0; q < 10; q++) {
+                    if (glyph & (0x200 >> q)) {
                         concat(binary, "1");
                     } else {
                         concat(binary, "0");
@@ -659,8 +661,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                 if (debug) {
                     printf("[%d] ", glyph);
                 }
-                for (int p = 0; p < 8; p++) {
-                    if (glyph & (0x80 >> p)) {
+                for (q = 0; q < 8; q++) {
+                    if (glyph & (0x80 >> q)) {
                         concat(binary, "1");
                     } else {
                         concat(binary, "0");
@@ -692,8 +694,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                         printf("[%d] ", glyph);
                     }
 
-                    for (int p = 0; p < 6; p++) {
-                        if (glyph & (0x20 >> p)) {
+                    for (q = 0; q < 6; q++) {
+                        if (glyph & (0x20 >> q)) {
                             concat(binary, "1");
                         } else {
                             concat(binary, "0");
@@ -724,8 +726,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                         printf("[%d] ", glyph);
                     }
 
-                    for (int p = 0; p < 5; p++) {
-                        if (glyph & (0x10 >> p)) {
+                    for (q = 0; q < 5; q++) {
+                        if (glyph & (0x10 >> q)) {
                             concat(binary, "1");
                         } else {
                             concat(binary, "0");
@@ -756,8 +758,8 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
                         printf("[%d] ", glyph);
                     }
 
-                    for (int p = 0; p < 5; p++) {
-                        if (glyph & (0x10 >> p)) {
+                    for (q = 0; q < 5; q++) {
+                        if (glyph & (0x10 >> q)) {
                             concat(binary, "1");
                         } else {
                             concat(binary, "0");
@@ -829,7 +831,7 @@ int gm_encode(int gbdata[], int length, char binary[], int reader) {
 }
 
 void gm_add_ecc(char binary[], int data_posn, int layers, int ecc_level, int word[]) {
-    int data_cw, i, j, wp;
+    int data_cw, i, j, wp, p;
     int n1, b1, n2, b2, e1, b3, e2;
     int block_size, data_size, ecc_size;
     int data[1320], block[130];
@@ -843,7 +845,7 @@ void gm_add_ecc(char binary[], int data_posn, int layers, int ecc_level, int wor
 
     /* Convert from binary sream to 7-bit codewords */
     for (i = 0; i < data_posn; i++) {
-        for (int p = 0; p < 7; p++) {
+        for (p = 0; p < 7; p++) {
             if (binary[i * 7 + p] == '1') {
                 data[i] += (0x40 >> p);
             }