diff --git a/backend/aztec.c b/backend/aztec.c
index 35494b55..a14a5004 100644
--- a/backend/aztec.c
+++ b/backend/aztec.c
@@ -47,25 +47,42 @@ void insert(char binary_string[], int posn, char newbit)
 	binary_string[posn] = newbit;
 }
 
-int aztec_text_process(unsigned char source[], char binary_string[])
+int aztec_text_process(unsigned char source[], char binary_string[], int gs1)
 { /* Encode input data into a binary string */
 	int i, j, k, bytes;
 	int charmap[ustrlen(source)], typemap[ustrlen(source)], maplength;
 	int curtable, newtable, lasttable, chartype;
 	int blockmap[2][ustrlen(source)], blocks;
 
-
 	/* Lookup input string in encoding table */
+	maplength = 0;
+	if((gs1) && (i == 0)) {
+		/* Add FNC1 to beginning of GS1 messages */
+		charmap[maplength] = 0;
+		typemap[maplength] = 8;
+		maplength++;
+		charmap[maplength] = 400;
+		typemap[maplength] = 8;
+		maplength++;
+	}
 	for(i = 0; i < ustrlen(source); i++) {
 		if(source[i] > 127) {
-			charmap[i] = source[i];
-			typemap[i] = BINARY;
+			charmap[maplength] = source[i];
+			typemap[maplength] = BINARY;
 		} else {
-			charmap[i] = AztecSymbolChar[source[i]];
-			typemap[i] = AztecCodeSet[source[i]];
+			charmap[maplength] = AztecSymbolChar[source[i]];
+			typemap[maplength] = AztecCodeSet[source[i]];
 		}
+		if((gs1) && (source[i] == '[')) {
+			/* FNC1 represented by FLG(0) */
+			charmap[maplength] = 0;
+			typemap[maplength] = 8;
+			maplength++;
+			charmap[maplength] = 400;
+			typemap[maplength] = 8;
+		}
+		maplength++;
 	}
-	maplength = ustrlen(source);
 	
 	/* Look for double character encoding possibilities */
 	i = 0;
@@ -522,7 +539,11 @@ int aztec_text_process(unsigned char source[], char binary_string[])
 			case LOWER:
 			case MIXED:
 			case PUNC:
-				concat(binary_string, hexbit[charmap[i]]);
+				if(charmap[i] >= 400) {
+					concat(binary_string, tribit[charmap[i] - 400]);
+				} else {
+					concat(binary_string, hexbit[charmap[i]]);
+				}
 				break;
 			case DIGIT:
 				concat(binary_string, pentbit[charmap[i]]);
@@ -556,12 +577,13 @@ int aztec(struct zint_symbol *symbol, unsigned char source[])
 	unsigned int data_part[1500], ecc_part[840];
 	unsigned char desc_data[4], desc_ecc[6];
 	int err_code, ecc_level, compact, data_length, data_maxsize, codeword_size, adjusted_length;
-	int remainder, padbits, count;
+	int remainder, padbits, count, gs1;
 	
 	memset(binary_string,0,20000);
 	memset(adjusted_string,0,20000);
 
-	err_code = aztec_text_process(source, binary_string);
+	if(symbol->input_mode == GS1_MODE) { gs1 = 1; } else { gs1 = 0; }
+	err_code = aztec_text_process(source, binary_string, gs1);
 
 	if(err_code != 0) {
 		strcpy(symbol->errtxt, "Input too long or too many extended ASCII characters [921]");
diff --git a/backend/aztec.h b/backend/aztec.h
index 27bcd5b7..f34814e8 100644
--- a/backend/aztec.h
+++ b/backend/aztec.h
@@ -245,6 +245,8 @@ static char *pentbit[32] = {"0000", "0001", "0010", "0011", "0100", "0101", "011
 	"1010", "1011", "1100", "1101", "1110", "1111"
 };
 
+static char *tribit[8] = {"000", "001", "010", "011", "100", "101", "110", "111"};
+
 static int AztecSizes[32] = { /* Codewords per symbol */
 	21, 48, 60, 88, 120, 156, 196, 240, 230, 272, 316, 364, 416, 470, 528, 588, 652, 720, 790,
 	864, 940, 1020, 920, 992, 1066, 1144, 1224, 1306, 1392, 1480, 1570, 1664
diff --git a/backend/gs1.c b/backend/gs1.c
index 338428fc..1df18138 100644
--- a/backend/gs1.c
+++ b/backend/gs1.c
@@ -59,7 +59,7 @@ int gs1_verify(struct zint_symbol *symbol, unsigned char source[], char reduced[
 	
 	/* remove the following to make this code work */
 	read_this = NOW;
-	
+
 	/* BogDan... Happy New Year! I've been trying to contact you but can't get through!
 	  the message keeps bouncing back to me. I've put a message on the developers forum on SF instead */
 	
@@ -90,7 +90,7 @@ int gs1_verify(struct zint_symbol *symbol, unsigned char source[], char reduced[
 	ai_latch = 0;
 	for(i = 0; i < ustrlen(source); i++) {
 		ai_length += j;
-		if((j == 1) && ((source[i] < '0') || (source[i] > '9'))) { ai_latch = 1; }
+		if(((j == 1) && (source[i] != ']')) && ((source[i] < '0') || (source[i] > '9'))) { ai_latch = 1; }
 		if(source[i] == '[') { bracket_level++; j = 1; }
 		if(source[i] == ']') {
 			bracket_level--;
diff --git a/backend/library.c b/backend/library.c
index 5b8d2d8b..ae97a592 100644
--- a/backend/library.c
+++ b/backend/library.c
@@ -201,6 +201,7 @@ int gs1_compliant(int symbology)
 		case BARCODE_RSS14_OMNI_CC:
 		case BARCODE_RSS_EXPSTACK_CC:
 		case BARCODE_CODE16K:
+		case BARCODE_AZTEC:
 			result = 1;
 			break;
 	}