diff --git a/backend/2of5.c b/backend/2of5.c
index f29dabf5..5089e3ec 100644
--- a/backend/2of5.c
+++ b/backend/2of5.c
@@ -244,6 +244,7 @@ int itf14(struct zint_symbol *symbol, unsigned char source[])
 	int i, error_number, h, zeroes;
 	unsigned int count, check_digit;
 	char localstr[15];
+	char checkstr[3];
 	
 	error_number = 0;
 
@@ -282,8 +283,9 @@ int itf14(struct zint_symbol *symbol, unsigned char source[])
 	}
 	check_digit = 10 - (count%10);
 	if (check_digit == 10) { check_digit = 0; }
-	localstr[h] = itoc(check_digit);
-	localstr[h + 1] = '\0';
+	checkstr[0] = itoc(check_digit);
+	checkstr[1] = '\0';
+	concat(localstr, checkstr);
 	error_number = interleaved_two_of_five(symbol, (unsigned char *)localstr);
 	strcpy(symbol->text, localstr);
 	return error_number;
@@ -328,7 +330,7 @@ int dpleit(struct zint_symbol *symbol, unsigned char source[])
 	if (check_digit == 10) { check_digit = 0; }
 	checkstr[0] = itoc(check_digit);
 	checkstr[1] = '\0';
-	strcpy(localstr, checkstr);
+	concat(localstr, checkstr);
 	error_number = interleaved_two_of_five(symbol, (unsigned char *)localstr);
 	strcpy(symbol->text, localstr);
 	return error_number;
@@ -355,8 +357,8 @@ int dpident(struct zint_symbol *symbol, unsigned char source[])
 	strcpy(localstr, "");
 	zeroes = 11 - h;
 	for(i = 0; i < zeroes; i++)
-		strcpy(localstr, "0");
-	strcpy(localstr, (char *)source);
+		concat(localstr, "0");
+	concat(localstr, (char *)source);
 	
 	for (i = 10; i >= 0; i--)
 	{
@@ -371,7 +373,7 @@ int dpident(struct zint_symbol *symbol, unsigned char source[])
 	if (check_digit == 10) { check_digit = 0; }
 	checkstr[0] = itoc(check_digit);
 	checkstr[1] = '\0';
-	strcpy(localstr, checkstr);
+	concat(localstr, checkstr);
 	error_number = interleaved_two_of_five(symbol, (unsigned char *)localstr);
 	strcpy(symbol->text, localstr);
 	return error_number;
diff --git a/backend/code.c b/backend/code.c
index 669008ec..0d018657 100644
--- a/backend/code.c
+++ b/backend/code.c
@@ -247,12 +247,14 @@ int pharmazentral(struct zint_symbol *symbol, unsigned char source[])
 	
 	int i, error_number;
 	unsigned int h, count, check_digit;
+	char localstr[8];
+	int zeroes;
 	
 	error_number = 0;
 
 	count = 0;
 	h = ustrlen(source);
-	if(h != 6) {
+	if(h > 6) {
 		strcpy(symbol->errtxt, "Input wrong length [521]");
 		return ERROR_TOO_LONG;
 	}
@@ -262,23 +264,29 @@ int pharmazentral(struct zint_symbol *symbol, unsigned char source[])
 		return error_number;
 	}
 	
-	for (i = 0; i < h; i++)
+	strcpy(localstr, "");
+	zeroes = 6 - h;
+	for(i = 0; i < zeroes; i++)
+		concat(localstr, "0");
+	concat(localstr, (char *)source);
+	
+	for (i = 0; i < 6; i++)
 	{
-		count += (i + 2) * ctoi(source[i]);
+		count += (i + 2) * ctoi(localstr[i]);
 	}
 
-	for(i = h + 1; i >= 1; i--)
+	for(i = 7; i >= 1; i--)
 	{
-		source[i] = source[i - 1];
+		localstr[i] = localstr[i - 1];
 	}
-	source[0] = '-';
+	localstr[0] = '-';
 	
 	check_digit = count%11;
 	if (check_digit == 11) { check_digit = 0; }
-	source[h + 1] = itoc(check_digit);
-	source[h + 2] = '\0';
-	error_number = c39(symbol, source);
-	strcpy(symbol->text, (char*)source);
+	localstr[7] = itoc(check_digit);
+	localstr[8] = '\0';
+	error_number = c39(symbol, (unsigned char *)localstr);
+	strcpy(symbol->text, localstr);
 	return error_number;
 }
 
diff --git a/backend/code128.c b/backend/code128.c
index 1c78bc93..2ff95dd5 100644
--- a/backend/code128.c
+++ b/backend/code128.c
@@ -872,7 +872,7 @@ int nve_18(struct zint_symbol *symbol, unsigned char source[])
 {
 	/* Add check digit if encoding an NVE18 symbol */
 	int error_number, zeroes, i, nve_check, total_sum, sourcelen;
-	unsigned char localstr[20], checkstr[3];
+	char localstr[20], checkstr[3];
 	
 	sourcelen = ustrlen(source);
 	if(sourcelen > 17) {
@@ -903,10 +903,11 @@ int nve_18(struct zint_symbol *symbol, unsigned char source[])
 
 	}
 	nve_check = 10 - total_sum%10;
+	if(nve_check == 10) { nve_check = 0; }
 	checkstr[1] = '\0';
 	checkstr[0] = itoc(nve_check);
 	concat(localstr, checkstr);
-	error_number = code_128(symbol, localstr);
+	error_number = code_128(symbol, (unsigned char *)localstr);
 	
 	return error_number;
 }
@@ -914,7 +915,7 @@ int nve_18(struct zint_symbol *symbol, unsigned char source[])
 int ean_14(struct zint_symbol *symbol, unsigned char source[])
 {
 	/* EAN-14 - A version of EAN-128 */
-	int input_length, i, count, check_digit;
+	int input_length, i, j, count, check_digit;
 	int error_number, zeroes;
 	unsigned char ean128_equiv[20];
 	
@@ -934,7 +935,9 @@ int ean_14(struct zint_symbol *symbol, unsigned char source[])
 	concat((char*)ean128_equiv, "[01]");
 	zeroes = 13 - input_length;
 	for(i = 0; i < zeroes; i++) {
-		concat(ean128_equiv, "0");
+		j = ustrlen(ean128_equiv);
+		ean128_equiv[j] = '0';
+		ean128_equiv[j + 1] = '\0';
 	}
 	concat((char*)ean128_equiv, (char*)source);