diff --git a/backend/common.c b/backend/common.c
index f3dfabf1..6ed92fe1 100644
--- a/backend/common.c
+++ b/backend/common.c
@@ -141,7 +141,7 @@ INTERNAL int posn(const char set_string[], const char data) {
 /* Returns the number of times a character occurs in a string */
 INTERNAL int ustrchr_cnt(const unsigned char string[], const size_t length, const unsigned char c) {
     int count = 0;
-    int i;
+    unsigned int i;
     for (i = 0; i < length; i++) {
         if (string[i] == c) {
             count++;
@@ -408,12 +408,12 @@ INTERNAL void pn_define_mode(char* mode, const unsigned int data[], const size_t
     memcpy(prev_costs, (*head_costs)(state), num_modes * sizeof(unsigned int));
 
     /* Calculate costs using dynamic programming */
-    for (i = 0, cm_i = 0; i < length; i++, cm_i += num_modes) {
+    for (i = 0, cm_i = 0; i < (int) length; i++, cm_i += num_modes) {
         memset(cur_costs, 0, num_modes * sizeof(unsigned int));
 
         (*cur_cost)(state, data, length, i, char_modes, prev_costs, cur_costs);
 
-        if (eod_cost && i == length - 1) { /* Add end of data costs if last character */
+        if (eod_cost && i == (int) length - 1) { /* Add end of data costs if last character */
             for (j = 0; j < num_modes; j++) {
                 if (char_modes[cm_i + j]) {
                     cur_costs[j] += (*eod_cost)(state, j);
diff --git a/backend/gb18030.c b/backend/gb18030.c
index 7be3f9a7..89c2bd01 100644
--- a/backend/gb18030.c
+++ b/backend/gb18030.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -2868,8 +2868,8 @@ INTERNAL int gb18030_wctomb_zint(unsigned int* r1, unsigned int* r2, unsigned in
 
 /* Convert UTF-8 string to GB 18030 and place in array of ints */
 INTERNAL int gb18030_utf8tomb(struct zint_symbol *symbol, const unsigned char source[], size_t* p_length, unsigned int* gbdata) {
-    int i, j, error_number, ret;
-    unsigned int length;
+    int error_number, ret;
+    unsigned int i, j, length;
 #ifndef _MSC_VER
     unsigned int utfdata[*p_length + 1];
 #else
@@ -2923,9 +2923,10 @@ INTERNAL int gb18030_utf8tosb(int eci, const unsigned char source[], size_t* p_l
 
 /* Copy byte input stream to array of ints, putting double-bytes that match HANXIN Chinese mode in single entry, and quad-bytes in 2 entries */
 INTERNAL void gb18030_cpy(const unsigned char source[], size_t* p_length, unsigned int* gbdata) {
-    int i, j, done;
-    unsigned int length;
+    unsigned int i, j, length;
+    int done;
     unsigned char c1, c2, c3, c4;
+
     for (i = 0, j = 0, length = *p_length; i < length; i++, j++) {
         done = 0;
         c1 = source[i];
diff --git a/backend/gb2312.c b/backend/gb2312.c
index 3b48f10c..deb934c3 100644
--- a/backend/gb2312.c
+++ b/backend/gb2312.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -1501,7 +1501,7 @@ static const Summary16 gb2312_uni2indx_pageff[15] = {
 
 INTERNAL int gb2312_wctomb_zint(unsigned int* r, unsigned int wc) {
     const Summary16 *summary = NULL;
-    if (wc >= 0x0000 && wc < 0x0460) {
+    if (wc < 0x0460) {
         if (wc == 0x00b7) { /* ZINT: Patched to duplicate map to 0xA1A4 */
             *r = 0xA1A4;
             return 2;
@@ -1542,8 +1542,8 @@ INTERNAL int gb2312_wctomb_zint(unsigned int* r, unsigned int wc) {
 
 /* Convert UTF-8 string to GB 2312 (EUC-CN) and place in array of ints */
 INTERNAL int gb2312_utf8tomb(struct zint_symbol *symbol, const unsigned char source[], size_t* p_length, unsigned int* gbdata) {
-    int i, error_number;
-    unsigned int length;
+    int error_number;
+    unsigned int i, length;
 #ifndef _MSC_VER
     unsigned int utfdata[*p_length + 1];
 #else
@@ -1591,9 +1591,9 @@ INTERNAL int gb2312_utf8tosb(int eci, const unsigned char source[], size_t* p_le
 
 /* Copy byte input stream to array of ints, putting double-bytes that match GRIDMATRIX Chinese mode in single entry */
 INTERNAL void gb2312_cpy(const unsigned char source[], size_t* p_length, unsigned int* gbdata) {
-    int i, j;
-    unsigned int length;
+    unsigned int i, j, length;
     unsigned char c1, c2;
+
     for (i = 0, j = 0, length = *p_length; i < length; i++, j++) {
         if (length - i >= 2) {
             c1 = source[i];
diff --git a/backend/gridmtx.c b/backend/gridmtx.c
index 8fe11b57..98060180 100644
--- a/backend/gridmtx.c
+++ b/backend/gridmtx.c
@@ -1,7 +1,7 @@
 /*  gridmtx.c - Grid Matrix
 
     libzint - the open source barcode library
-    Copyright (C) 2009-2017 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2009-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -52,8 +52,8 @@
 static const char numeral_nondigits[] = " +-.,"; /* Non-digit numeral set, excluding EOL (carriage return/linefeed) */
 
 /* Whether in numeral or not. If in numeral, *p_numeral_end is set to position after numeral, and *p_numeral_cost is set to per-numeral cost */
-static int in_numeral(const unsigned int gbdata[], const size_t length, const int posn, unsigned int* p_numeral_end, unsigned int* p_numeral_cost) {
-    int i, digit_cnt, nondigit, nondigit_posn;
+static int in_numeral(const unsigned int gbdata[], const size_t length, const unsigned int posn, unsigned int* p_numeral_end, unsigned int* p_numeral_cost) {
+    unsigned int i, digit_cnt, nondigit, nondigit_posn;
 
     if (posn < *p_numeral_end) {
         return 1;
@@ -128,6 +128,7 @@ static unsigned int head_costs[GM_NUM_MODES] = {
 };
 
 static unsigned int* gm_head_costs(unsigned int state[]) {
+    (void)state; /* Unused */
     return head_costs;
 }
 
@@ -143,6 +144,7 @@ static unsigned int gm_switch_cost(unsigned int state[], const int k, const int
         /*B*/ {  4 * GM_MULT,  (4 + 2) * GM_MULT,  4 * GM_MULT,  4 * GM_MULT,  4 * GM_MULT,                  0 },
     };
 
+    (void)state; /* Unused */
     return switch_costs[k][j];
 }
 
@@ -153,6 +155,7 @@ static unsigned int gm_eod_cost(unsigned int state[], const int k) {
         13 * GM_MULT, 10 * GM_MULT, 5 * GM_MULT, 5 * GM_MULT, 10 * GM_MULT, 4 * GM_MULT
     };
 
+    (void)state; /* Unused */
     return eod_costs[k];
 }
 
@@ -170,8 +173,8 @@ static void gm_cur_cost(unsigned int state[], const unsigned int gbdata[], const
     lower = gbdata[i] >= 'a' && gbdata[i] <= 'z';
     upper = gbdata[i] >= 'A' && gbdata[i] <= 'Z';
     control = !space && !numeric && !lower && !upper && gbdata[i] < 0x7F; /* Exclude DEL */
-    double_digit = i < length - 1 && numeric && gbdata[i + 1] >= '0' && gbdata[i + 1] <= '9';
-    eol = i < length - 1 && gbdata[i] == 13 && gbdata[i + 1] == 10;
+    double_digit = i < (int) length - 1 && numeric && gbdata[i + 1] >= '0' && gbdata[i + 1] <= '9';
+    eol = i < (int) length - 1 && gbdata[i] == 13 && gbdata[i + 1] == 10;
 
     /* Hanzi mode can encode anything */
     cur_costs[GM_H] = prev_costs[GM_H] + (double_digit || eol ? 39 : 78); /* (6.5 : 13) * GM_MULT */
@@ -254,7 +257,8 @@ static int gm_encode(unsigned int gbdata[], const size_t length, char binary[],
     /* 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, last_mode;
+    unsigned int sp;
+    int current_mode, last_mode;
     unsigned int glyph = 0;
     int c1, c2, done;
     int p = 0, ppos;
@@ -730,7 +734,7 @@ static void gm_add_ecc(const char binary[], const size_t data_posn, const int la
     }
 
     /* Convert from binary stream to 7-bit codewords */
-    for (i = 0; i < data_posn; i++) {
+    for (i = 0; i < (int) data_posn; i++) {
         for (p = 0; p < 7; p++) {
             if (binary[i * 7 + p] == '1') {
                 data[i] += (0x40 >> p);
diff --git a/backend/hanxin.c b/backend/hanxin.c
index 33313585..cac60cc8 100644
--- a/backend/hanxin.c
+++ b/backend/hanxin.c
@@ -1,7 +1,7 @@
 /*  hanxin.c - Han Xin Code
 
     libzint - the open source barcode library
-    Copyright (C) 2009-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2009-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -298,8 +298,8 @@ static int lookup_text2(unsigned int input) {
 #define HX_MULT 6
 
 /* Whether in numeric or not. If in numeric, *p_end is set to position after numeric, and *p_cost is set to per-numeric cost */
-static int in_numeric(const unsigned int gbdata[], const size_t length, const int posn, unsigned int* p_end, unsigned int* p_cost) {
-    int i, digit_cnt;
+static int in_numeric(const unsigned int gbdata[], const size_t length, const unsigned int posn, unsigned int* p_end, unsigned int* p_cost) {
+    unsigned int i, digit_cnt;
 
     if (posn < *p_end) {
         return 1;
@@ -320,7 +320,7 @@ static int in_numeric(const unsigned int gbdata[], const size_t length, const in
 }
 
 /* Whether in four-byte or not. If in four-byte, *p_fourbyte is set to position after four-byte, and *p_fourbyte_cost is set to per-position cost */
-static int in_fourbyte(const unsigned int gbdata[], const size_t length, const int posn, unsigned int* p_end, unsigned int* p_cost) {
+static int in_fourbyte(const unsigned int gbdata[], const size_t length, const unsigned int posn, unsigned int* p_end, unsigned int* p_cost) {
     if (posn < *p_end) {
         return 1;
     }
@@ -353,6 +353,7 @@ static unsigned int* hx_head_costs(unsigned int state[]) {
         4 * HX_MULT, 4 * HX_MULT, (4 + 13) * HX_MULT, 4 * HX_MULT, 4 * HX_MULT, 4 * HX_MULT, 0
     };
 
+    (void)state; /* Unused */
     return head_costs;
 }
 
@@ -369,6 +370,7 @@ static unsigned int hx_switch_cost(unsigned int state[], const int k, const int
         /*F*/ {        4 * HX_MULT,        4 * HX_MULT,      (4 + 13) * HX_MULT,        4 * HX_MULT,        4 * HX_MULT,        4 * HX_MULT,  0 },
     };
 
+    (void)state; /* Unused */
     return switch_costs[k][j];
 }
 
@@ -379,6 +381,7 @@ static unsigned int hx_eod_cost(unsigned int state[], const int k) {
         10 * HX_MULT, 6 * HX_MULT, 0, 12 * HX_MULT, 12 * HX_MULT, 15 * HX_MULT, 0
     };
 
+    (void)state; /* Unused */
     return eod_costs[k];
 }
 
@@ -444,7 +447,7 @@ static void hx_define_mode(char* mode, const unsigned int gbdata[], const size_t
 
 /* Convert input data to binary stream */
 static void calculate_binary(char binary[], char mode[], unsigned int source[], const size_t length, const int eci, int debug) {
-    int position = 0;
+    unsigned int position = 0;
     int i, count, encoding_value;
     int first_byte, second_byte;
     int third_byte, fourth_byte;
@@ -1401,7 +1404,7 @@ INTERNAL int han_xin(struct zint_symbol *symbol, const unsigned char source[], s
         int done = 0;
         if (symbol->eci != 29) { /* Unless ECI 29 (GB) */
             /* Try single byte (Latin) conversion first */
-            int error_number = gb2312_utf8tosb(symbol->eci && symbol->eci <= 899 ? symbol->eci : 3, source, &length, gbdata);
+            int error_number = gb18030_utf8tosb(symbol->eci && symbol->eci <= 899 ? symbol->eci : 3, source, &length, gbdata);
             if (error_number == 0) {
                 done = 1;
             } else if (symbol->eci && symbol->eci <= 899) {
diff --git a/backend/qr.c b/backend/qr.c
index 29f0d33e..669d1d4d 100644
--- a/backend/qr.c
+++ b/backend/qr.c
@@ -1,7 +1,7 @@
 /* qr.c Handles QR Code, Micro QR Code, UPNQR and rMQR
 
     libzint - the open source barcode library
-    Copyright (C) 2009 - 2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2009 - 2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -76,8 +76,8 @@ static int is_alpha(const unsigned int glyph, const int gs1) {
 #define QR_MULT 6
 
 /* Whether in numeric or not. If in numeric, *p_end is set to position after numeric, and *p_cost is set to per-numeric cost */
-static int in_numeric(const unsigned int jisdata[], const size_t length, const int posn, unsigned int* p_end, unsigned int* p_cost) {
-    int i, digit_cnt;
+static int in_numeric(const unsigned int jisdata[], const size_t length, const unsigned int posn, unsigned int* p_end, unsigned int* p_cost) {
+    unsigned int i, digit_cnt;
 
     if (posn < *p_end) {
         return 1;
@@ -98,7 +98,7 @@ static int in_numeric(const unsigned int jisdata[], const size_t length, const i
 }
 
 /* Whether in alpha or not. If in alpha, *p_end is set to position after alpha, and *p_cost is set to per-alpha cost. For GS1, *p_pcent set if 2nd char percent */
-static int in_alpha(const unsigned int jisdata[], const size_t length, const int posn, unsigned int* p_end, unsigned int* p_cost, unsigned int* p_pcent, unsigned int gs1) {
+static int in_alpha(const unsigned int jisdata[], const size_t length, const unsigned int posn, unsigned int* p_end, unsigned int* p_cost, unsigned int* p_pcent, unsigned int gs1) {
     int two_alphas;
 
     if (posn < *p_end) {
@@ -200,6 +200,7 @@ static unsigned int* qr_head_costs(unsigned int state[]) {
 
 /* Costs of switching modes from k to j */
 static unsigned int qr_switch_cost(unsigned int state[], const int k, const int j) {
+    (void)k; /* Unused */
     return state[j]; /* Same as head cost */
 }
 
@@ -326,7 +327,7 @@ static int terminator_bits(const int version) {
 /* Convert input data to a binary stream and add padding */
 static void qr_binary(unsigned char datastream[], const int version, const int target_codewords, const char mode[], const unsigned int jisdata[], const size_t length,
             const int gs1, const int eci, const int est_binlen, const int debug) {
-    int position = 0;
+    unsigned int position = 0;
     int i;
     int termbits, padbits;
     int current_binlen, current_bytes;
@@ -360,7 +361,7 @@ static void qr_binary(unsigned char datastream[], const int version, const int t
     }
 
     if (debug & ZINT_DEBUG_PRINT) {
-        for (i = 0; i < length; i++) {
+        for (i = 0; i < (int) length; i++) {
             printf("%c", mode[i]);
         }
         printf("\n");
@@ -1428,9 +1429,8 @@ static size_t blockLength(const size_t start,const char inputMode[],const size_t
 
 static int getBinaryLength(const int version, char inputMode[], const unsigned int inputData[], const size_t inputLength, const int gs1, const int eci, const int debug) {
     /* Calculate the actual bitlength of the proposed binary string */
-    size_t i;
+    size_t i, j;
     char currentMode;
-    int    j;
     int count = 0;
     int alphalength;
     int blocklength;
@@ -1830,6 +1830,8 @@ static void micro_qr_m1(struct zint_symbol *symbol, char binary_data[]) {
     }
 #ifdef ZINT_TEST
     if (symbol->debug & ZINT_DEBUG_TEST) debug_test_codeword_dump(symbol, data_blocks, data_codewords);
+#else
+    (void)symbol; /* Unused */
 #endif
 
     /* Calculate Reed-Solomon error codewords */
@@ -1911,6 +1913,8 @@ static void micro_qr_m2(struct zint_symbol *symbol, char binary_data[], const in
     }
 #ifdef ZINT_TEST
     if (symbol->debug & ZINT_DEBUG_TEST) debug_test_codeword_dump(symbol, data_blocks, data_codewords);
+#else
+    (void)symbol; /* Unused */
 #endif
 
     /* Calculate Reed-Solomon error codewords */
@@ -2026,6 +2030,8 @@ static void micro_qr_m3(struct zint_symbol *symbol, char binary_data[], const in
     }
 #ifdef ZINT_TEST
     if (symbol->debug & ZINT_DEBUG_TEST) debug_test_codeword_dump(symbol, data_blocks, data_codewords);
+#else
+    (void)symbol; /* Unused */
 #endif
 
     /* Calculate Reed-Solomon error codewords */
@@ -2116,6 +2122,8 @@ static void micro_qr_m4(struct zint_symbol *symbol, char binary_data[], const in
     }
 #ifdef ZINT_TEST
     if (symbol->debug & ZINT_DEBUG_TEST) debug_test_codeword_dump(symbol, data_blocks, data_codewords);
+#else
+    (void)symbol; /* Unused */
 #endif
 
     /* Calculate Reed-Solomon error codewords */
@@ -2168,8 +2176,8 @@ static void micro_setup_grid(unsigned char* grid,const int size) {
 static void micro_populate_grid(unsigned char* grid,const int size,const char full_stream[]) {
     int direction = 1; /* up */
     int row = 0; /* right hand side */
-    size_t n;
-    int i, y;
+    size_t n, i;
+    int y;
 
     n = strlen(full_stream);
     y = size - 1;
@@ -2334,8 +2342,7 @@ static int micro_apply_bitmask(unsigned char *grid,const int size) {
 }
 
 INTERNAL int microqr(struct zint_symbol *symbol, const unsigned char source[], size_t length) {
-    size_t i;
-    int    j, size;
+    size_t i, size, j;
     char full_stream[200];
 
     unsigned int jisdata[40];
@@ -2656,7 +2663,7 @@ INTERNAL int upnqr(struct zint_symbol *symbol, const unsigned char source[], siz
     switch (symbol->input_mode & 0x07) {
         case DATA_MODE:
             /* Input is already in ISO-8859-2 format */
-            for (i = 0; i < length; i++) {
+            for (i = 0; i < (int) length; i++) {
                 jisdata[i] = source[i];
                 mode[i] = 'B';
             }
@@ -2671,7 +2678,7 @@ INTERNAL int upnqr(struct zint_symbol *symbol, const unsigned char source[], siz
                 strcpy(symbol->errtxt, "572: Invalid characters in input data");
                 return error_number;
             }
-            for (i = 0; i < length; i++) {
+            for (i = 0; i < (int) length; i++) {
                 jisdata[i] = preprocessed[i];
                 mode[i] = 'B';
             }
@@ -2742,7 +2749,7 @@ INTERNAL int upnqr(struct zint_symbol *symbol, const unsigned char source[], siz
     return 0;
 }
 
-static void setup_rmqr_grid(unsigned char* grid,const int h_size,const int v_size,const int version) {
+static void setup_rmqr_grid(unsigned char* grid, const int h_size, const int v_size) {
     int i, j;
     char alignment[] = {0x1F, 0x11, 0x15, 0x11, 0x1F};
     int h_version, finder_position;
@@ -3033,7 +3040,7 @@ INTERNAL int rmqr(struct zint_symbol *symbol, const unsigned char source[], size
         }
     }
 
-    setup_rmqr_grid(grid, h_size, v_size, version);
+    setup_rmqr_grid(grid, h_size, v_size);
     populate_grid(grid, h_size, v_size, fullstream, rmqr_total_codewords[version]);
 
     /* apply bitmask */
diff --git a/backend/sjis.c b/backend/sjis.c
index d7933579..b553f9ba 100644
--- a/backend/sjis.c
+++ b/backend/sjis.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -1443,7 +1443,7 @@ static const Summary16 jisx0208_uni2indx_pageff[15] = {
 
 static int jisx0208_wctomb(unsigned int* r, unsigned int wc) {
     const Summary16 *summary = NULL;
-    if (wc >= 0x0000 && wc < 0x0100) {
+    if (wc < 0x0100) {
         summary = &jisx0208_uni2indx_page00[(wc>>4)];
     } else if (wc >= 0x0300 && wc < 0x0460) {
         summary = &jisx0208_uni2indx_page03[(wc>>4)-0x030];
@@ -1513,8 +1513,8 @@ INTERNAL int sjis_wctomb_zint(unsigned int* r, unsigned int wc) {
 
 /* Convert UTF-8 string to Shift JIS and place in array of ints */
 INTERNAL int sjis_utf8tomb(struct zint_symbol *symbol, const unsigned char source[], size_t* p_length, unsigned int* jisdata) {
-    int i, error_number;
-    unsigned int length;
+    int error_number;
+    unsigned int i, length;
 #ifndef _MSC_VER
     unsigned int utfdata[*p_length + 1];
 #else
@@ -1558,9 +1558,9 @@ INTERNAL int sjis_utf8tosb(int eci, const unsigned char source[], size_t* p_leng
 
 /* Copy byte input stream to array of ints, putting double-bytes that match QR Kanji mode in single entry */
 INTERNAL void sjis_cpy(const unsigned char source[], size_t* p_length, unsigned int* jisdata) {
-    int i, j;
-    unsigned int jis, length;
+    unsigned int i, j, jis, length;
     unsigned char c;
+
     for (i = 0, j = 0, length = *p_length; i < length; i++, j++) {
         c = source[i];
         if (((c >= 0x81 && c <= 0x9F) || (c >= 0xE0 && c <= 0xEB)) && length - i >= 2) {
diff --git a/backend/tests/test_gb18030.c b/backend/tests/test_gb18030.c
index e06c77b6..0c91b058 100644
--- a/backend/tests/test_gb18030.c
+++ b/backend/tests/test_gb18030.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -273,7 +273,7 @@ static void test_gb18030_cpy(void)
         int length;
         int ret;
         size_t ret_length;
-        unsigned int expected_jisdata[20];
+        unsigned int expected_gbdata[20];
         char* comment;
     };
     // s/\/\*[ 0-9]*\*\//\=printf("\/*%3d*\/", line(".") - line("'<"))
@@ -287,17 +287,17 @@ static void test_gb18030_cpy(void)
 
     int data_size = sizeof(data) / sizeof(struct item);
 
-    unsigned int jisdata[40];
+    unsigned int gbdata[20];
 
     for (int i = 0; i < data_size; i++) {
 
         int length = data[i].length == -1 ? strlen(data[i].data) : data[i].length;
         size_t ret_length = length;
 
-        gb18030_cpy(data[i].data, &ret_length, jisdata);
+        gb18030_cpy(data[i].data, &ret_length, gbdata);
         assert_equal(ret_length, data[i].ret_length, "i:%d ret_length %zu != %zu\n", i, ret_length, data[i].ret_length);
         for (int j = 0; j < ret_length; j++) {
-            assert_equal(jisdata[j], data[i].expected_jisdata[j], "i:%d jisdata[%d] %04X != %04X\n", i, j, jisdata[j], data[i].expected_jisdata[j]);
+            assert_equal(gbdata[j], data[i].expected_gbdata[j], "i:%d gbdata[%d] %04X != %04X\n", i, j, gbdata[j], data[i].expected_gbdata[j]);
         }
     }
 
diff --git a/backend/tests/test_gb2312.c b/backend/tests/test_gb2312.c
index 22d934ff..f3130396 100644
--- a/backend/tests/test_gb2312.c
+++ b/backend/tests/test_gb2312.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -216,7 +216,7 @@ static void test_gb2312_cpy(void)
         int length;
         int ret;
         size_t ret_length;
-        unsigned int expected_jisdata[20];
+        unsigned int expected_gbdata[20];
         char* comment;
     };
     // s/\/\*[ 0-9]*\*\//\=printf("\/*%3d*\/", line(".") - line("'<"))
@@ -230,17 +230,17 @@ static void test_gb2312_cpy(void)
 
     int data_size = sizeof(data) / sizeof(struct item);
 
-    unsigned int jisdata[20];
+    unsigned int gbdata[20];
 
     for (int i = 0; i < data_size; i++) {
 
         int length = data[i].length == -1 ? strlen(data[i].data) : data[i].length;
         size_t ret_length = length;
 
-        gb2312_cpy(data[i].data, &ret_length, jisdata);
+        gb2312_cpy(data[i].data, &ret_length, gbdata);
         assert_equal(ret_length, data[i].ret_length, "i:%d ret_length %zu != %zu\n", i, ret_length, data[i].ret_length);
         for (int j = 0; j < ret_length; j++) {
-            assert_equal(jisdata[j], data[i].expected_jisdata[j], "i:%d jisdata[%d] %04X != %04X\n", i, j, jisdata[j], data[i].expected_jisdata[j]);
+            assert_equal(gbdata[j], data[i].expected_gbdata[j], "i:%d gbdata[%d] %04X != %04X\n", i, j, gbdata[j], data[i].expected_gbdata[j]);
         }
     }
 
diff --git a/backend/tests/test_hanxin.c b/backend/tests/test_hanxin.c
index 191d5fe2..2ac5c47a 100644
--- a/backend/tests/test_hanxin.c
+++ b/backend/tests/test_hanxin.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -144,6 +144,7 @@ static void test_input(void)
         /* 21*/ { UNICODE_MODE, 0, "Summer Palace Ticket for 6 June 2015 13:00;2015年6月6日夜01時00分PM頤和園のチケット;2015년6월6일13시오후여름궁전티켓.2015年6月6号下午13:00的颐和园门票;", -1, 0, 0, "(189) 27 38 C3 0A 35 F9 CF 99 92 F9 26 A3 E7 3E 76 C9 AE A3 7F CC 08 04 0C CD EE 44 06 C4", "T20 B64 N4 H(f)1 T1 H(f)1 T1 H(f)1 T2 H(f)9 B35 (GB 18030)" },
         /* 22*/ { UNICODE_MODE, 0, "\000\014\033 #/059:<@AMZ", 15, 0, 0, "2F 80 31 B7 1F AF E0 05 27 EB 2E CB E2 96 8F F0 00", "T15 (ASCII)" },
         /* 23*/ { UNICODE_MODE, 0, "Z[\\`alz{~\177", -1, 0, 0, "28 FE CF 4E 3E 92 FF 7E E7 CF 7F 00 00", "T10 (ASCII)" },
+        /* 24*/ { UNICODE_MODE, 26, "\2021\2033", -1, 0, 26, "81 A7 01 B1 D8 00 00 00 00", "ECI-26 H(f)1 (GB 18030)" },
     };
     int data_size = sizeof(data) / sizeof(struct item);
 
diff --git a/backend/tests/test_sjis.c b/backend/tests/test_sjis.c
index 38e94a5b..53f77c4b 100644
--- a/backend/tests/test_sjis.c
+++ b/backend/tests/test_sjis.c
@@ -1,6 +1,6 @@
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008-2019 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2020 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -236,9 +236,9 @@ static void test_sjis_cpy(void)
     struct item data[] = {
         /*  0*/ { "\351", -1, 0, 1, { 0xE9 }, "In QR Kanji mode first-byte range but only one byte" },
         /*  1*/ { "\351\141", -1, 0, 1, { 0xE961 }, "In QR Kanji mode range" },
-        /*  0*/ { "\201", -1, 0, 1, { 0x81 }, "In QR Kanji mode first-byte range but only one byte" },
-        /*  0*/ { "\201\141", -1, 0, 1, { 0x8161 }, "In QR Kanji mode range" },
-        /*  0*/ { "\201\077\201\100\237\374\237\375\340\077\340\100\353\277\353\300", -1, 0, 12, { 0x81, 0x3F, 0x8140, 0x9FFC, 0x9F, 0xFD, 0xE0, 0x3F, 0xE040, 0xEBBF, 0xEB, 0xC0 }, "" },
+        /*  2*/ { "\201", -1, 0, 1, { 0x81 }, "In QR Kanji mode first-byte range but only one byte" },
+        /*  3*/ { "\201\141", -1, 0, 1, { 0x8161 }, "In QR Kanji mode range" },
+        /*  4*/ { "\201\077\201\100\237\374\237\375\340\077\340\100\353\277\353\300", -1, 0, 12, { 0x81, 0x3F, 0x8140, 0x9FFC, 0x9F, 0xFD, 0xE0, 0x3F, 0xE040, 0xEBBF, 0xEB, 0xC0 }, "" },
     };
 
     int data_size = sizeof(data) / sizeof(struct item);