diff --git a/backend/aztec.c b/backend/aztec.c
index 73261efb..03d46b17 100644
--- a/backend/aztec.c
+++ b/backend/aztec.c
@@ -23,7 +23,7 @@
 #include <string.h>
 #include <stdlib.h>
 #ifdef _MSC_VER
-#include <malloc.h> 
+#include <malloc.h> 
 #endif
 #include "common.h"
 #include "aztec.h"
@@ -55,14 +55,14 @@ int aztec_text_process(unsigned char source[], char binary_string[], int gs1)
 	int i, j, k, bytes;
 	int curtable, newtable, lasttable, chartype, maplength, blocks, debug;
 #ifndef _MSC_VER
-	int charmap[ustrlen(source)], typemap[ustrlen(source)];
+	int charmap[ustrlen(source) * 2], typemap[ustrlen(source) * 2];
 	int blockmap[2][ustrlen(source)];
 #else
-        int* charmap = (int*)_alloca(ustrlen(source) * sizeof(int));
-        int* typemap = (int*)_alloca(ustrlen(source) * sizeof(int));
+        int* charmap = (int*)_alloca((ustrlen(source) * 2) * sizeof(int));
+        int* typemap = (int*)_alloca((ustrlen(source) * 2) * sizeof(int));
         int* blockmap[2];
-        blockmap[0] = (int*)_alloca(ustrlen(source) * sizeof(int));
-        blockmap[1] = (int*)_alloca(ustrlen(source) * sizeof(int));
+        blockmap[0] = (int*)_alloca(ustrlen(source) * sizeof(int));
+        blockmap[1] = (int*)_alloca(ustrlen(source) * sizeof(int));
 #endif
 	/* Lookup input string in encoding table */
 	maplength = 0;
diff --git a/backend/aztec.h b/backend/aztec.h
index f34814e8..93e0e278 100644
--- a/backend/aztec.h
+++ b/backend/aztec.h
@@ -241,7 +241,7 @@ static char *hexbit[32] = {"00000", "00001", "00010", "00011", "00100", "00101",
 	"10110", "10111", "11000", "11001", "11010", "11011", "11100", "11101", "11110", "11111"
 };
 
-static char *pentbit[32] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001",
+static char *pentbit[16] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001",
 	"1010", "1011", "1100", "1101", "1110", "1111"
 };
 
diff --git a/backend/code.c b/backend/code.c
index 63fccc5e..b3067d75 100644
--- a/backend/code.c
+++ b/backend/code.c
@@ -169,10 +169,12 @@ int c39(struct zint_symbol *symbol, unsigned char source[])
 	char check_digit;
 	int h, error_number;
 	char dest[1000];
+	char localstr[3];
 	
 	error_number = 0;
 	counter = 0;
 	strcpy(dest, "");
+	strcpy(localstr, "");
 
 	if((symbol->option_2 < 0) || (symbol->option_2 > 1)) {
 		symbol->option_2 = 0;
@@ -226,8 +228,8 @@ int c39(struct zint_symbol *symbol, unsigned char source[])
 		}
 		
 		h = ustrlen(source);
-		source[h] = check_digit;
-		source[h + 1] = '\0';
+		localstr[0] = check_digit;
+		localstr[1] = '\0';
 	}
 	
 	/* Stop character */
@@ -247,9 +249,11 @@ int c39(struct zint_symbol *symbol, unsigned char source[])
 	if(symbol->symbology == BARCODE_CODE39) {
 		ustrcpy(symbol->text, (unsigned char*)"*");
 		uconcat(symbol->text, source);
+		uconcat(symbol->text, (unsigned char*)localstr);
 		uconcat(symbol->text, (unsigned char*)"*");
 	} else {
 		ustrcpy(symbol->text, source);
+		uconcat(symbol->text, (unsigned char*)localstr);
 	}
 	return error_number;
 }
diff --git a/backend/common.c b/backend/common.c
index c0c8170a..14cd9fbb 100644
--- a/backend/common.c
+++ b/backend/common.c
@@ -92,7 +92,7 @@ int is_sane(char test_string[], unsigned char source[])
 { /* Verifies that a string only uses valid characters */
 	unsigned int i, j, latch;
 
-	for(i = 0; i < ustrlen(source); i++) {
+	for(i = 0; i < ustrlen(source) - 1; i++) {
 		latch = FALSE;
 		for(j = 0; j < strlen(test_string); j++) {
 			if (source[i] == test_string[j]) { latch = TRUE; } }
@@ -231,6 +231,19 @@ int is_stackable(int symbology) {
 	return 0;
 }
 
+int is_extendable(int symbology) {
+	/* Indicates which symbols can have addon */
+	if(symbology == BARCODE_EANX) { return 1; }
+	if(symbology == BARCODE_UPCA) { return 1; }
+	if(symbology == BARCODE_UPCE) { return 1; }
+	if(symbology == BARCODE_ISBNX) { return 1; }
+	if(symbology == BARCODE_UPCA_CC) { return 1; }
+	if(symbology == BARCODE_UPCE_CC) { return 1; }
+	if(symbology == BARCODE_EANX_CC) { return 1; }
+	
+	return 0;
+}
+
 int roundup(float input)
 {
 	float remainder;
diff --git a/backend/common.h b/backend/common.h
index 4ae05ed6..c439683e 100644
--- a/backend/common.h
+++ b/backend/common.h
@@ -53,6 +53,7 @@ extern void lookup(char set_string[], char *table[], char data, char dest[]);
 extern int posn(char set_string[], char data);
 extern void expand(struct zint_symbol *symbol, char data[]);
 extern int is_stackable(int symbology);
+extern int is_extendable(int symbology);
 extern int roundup(float input);
 extern int module_is_set(struct zint_symbol *symbol, int y_coord, int x_coord);
 extern void set_module(struct zint_symbol *symbol, int y_coord, int x_coord);
diff --git a/backend/library.c b/backend/library.c
index 0e08c547..b9539f22 100644
--- a/backend/library.c
+++ b/backend/library.c
@@ -389,6 +389,7 @@ int ZBarcode_Encode(struct zint_symbol *symbol, unsigned char *source)
 	int input_length;
 	
 	input_length = ustrlen(source);
+	
 #ifndef _MSC_VER
 	unsigned char preprocessed[input_length];
 #else
@@ -595,7 +596,7 @@ int ZBarcode_Print(struct zint_symbol *symbol)
 	/* int i, j;
 	
 	for(i = 0; i < symbol->rows; i++) {
-		for(j = 0; j < symbol->width / 7; j++) {
+		for(j = 0; j <= symbol->width / 7; j++) {
 			printf("%2.2X ", symbol->encoded_data[i][j]);
 		}
 		printf("\n");
diff --git a/backend/png.c b/backend/png.c
index c9bbc8d7..294fa3b9 100644
--- a/backend/png.c
+++ b/backend/png.c
@@ -555,13 +555,15 @@ int png_plot(struct zint_symbol *symbol, int rotate_angle)
 	latch = 0;
 	r = 0;
 	/* Isolate add-on text */
-	for(i = 0; i < ustrlen(local_text); i++) {
-		if (latch == 1) {
-			addon[r] = local_text[i];
-			r++;
-		}
-		if (symbol->text[i] == '+') {
-			latch = 1;
+	if(is_extendable(symbol->symbology)) {
+		for(i = 0; i < ustrlen(local_text); i++) {
+			if (latch == 1) {
+				addon[r] = local_text[i];
+				r++;
+			}
+			if (symbol->text[i] == '+') {
+				latch = 1;
+			}
 		}
 	}
 	addon[r] = '\0';
diff --git a/backend/ps.c b/backend/ps.c
index 90613de3..6e9db17c 100644
--- a/backend/ps.c
+++ b/backend/ps.c
@@ -154,13 +154,15 @@ int ps_plot(struct zint_symbol *symbol)
 	latch = 0;
 	r = 0;
 	/* Isolate add-on text */
-	for(i = 0; i < ustrlen(symbol->text); i++) {
-		if (latch == 1) {
-			addon[r] = symbol->text[i];
-			r++;
-		}
-		if (symbol->text[i] == '+') {
-			latch = 1;
+	if(is_extendable(symbol->symbology)) {
+		for(i = 0; i < ustrlen(symbol->text); i++) {
+			if (latch == 1) {
+				addon[r] = symbol->text[i];
+				r++;
+			}
+			if (symbol->text[i] == '+') {
+				latch = 1;
+			}
 		}
 	}
 	addon[r] = '\0';
diff --git a/backend/svg.c b/backend/svg.c
index 1ce3830c..b2b2ddbe 100644
--- a/backend/svg.c
+++ b/backend/svg.c
@@ -150,13 +150,15 @@ int svg_plot(struct zint_symbol *symbol)
 	latch = 0;
 	r = 0;
 	/* Isolate add-on text */
-	for(i = 0; i < ustrlen(symbol->text); i++) {
-		if (latch == 1) {
-			addon[r] = symbol->text[i];
-			r++;
-		}
-		if (symbol->text[i] == '+') {
-			latch = 1;
+	if(is_extendable(symbol->symbology)) {
+		for(i = 0; i < ustrlen(symbol->text); i++) {
+			if (latch == 1) {
+				addon[r] = symbol->text[i];
+				r++;
+			}
+			if (symbol->text[i] == '+') {
+				latch = 1;
+			}
 		}
 	}
 	addon[r] = '\0';
diff --git a/win32/test.bat b/win32/test.bat
index 2dba0ac8..38a8ab5b 100755
--- a/win32/test.bat
+++ b/win32/test.bat
@@ -613,11 +613,11 @@ zint -o bar92.eps -b 92 --border=10 -d "Demonstration Aztec Code symbol generate
 
 zint -o bar92.svg -b 92 --border=10 -d "Demonstration Aztec Code symbol generated by libzint"
 
-echo zint -o bar92a.png -b 92 --gs1 --border=10 -d "[01]98898765432106[02]13012345678909[10]1234567ABCDEFG[3202]012345[15]991231"
+zint -o bar92a.png -b 92 --gs1 --border=10 -d "[01]98898765432106[02]13012345678909[10]1234567ABCDEFG[3202]012345[15]991231"
 
-echo zint -o bar92a.eps -b 92 --gs1 --border=10 -d "[01]98898765432106[02]13012345678909[10]1234567ABCDEFG[3202]012345[15]991231"
+zint -o bar92a.eps -b 92 --gs1 --border=10 -d "[01]98898765432106[02]13012345678909[10]1234567ABCDEFG[3202]012345[15]991231"
 
-echo zint -o bar92a.svg -b 92 --gs1 --border=10 -d "[01]98898765432106[02]13012345678909[10]1234567ABCDEFG[3202]012345[15]991231"
+zint -o bar92a.svg -b 92 --gs1 --border=10 -d "[01]98898765432106[02]13012345678909[10]1234567ABCDEFG[3202]012345[15]991231"
 
 echo testing DAFT Code