diff --git a/backend/aztec.c b/backend/aztec.c
index 62d52b0b..f503c20a 100644
--- a/backend/aztec.c
+++ b/backend/aztec.c
@@ -1021,6 +1021,7 @@ int aztec(struct zint_symbol *symbol, unsigned char source[])
 	/* Now add the symbol descriptor */
 	memset(desc_data,0,4);
 	memset(desc_ecc,0,6);
+	memset(descriptor,0,42);
 
 	if(compact) {
 		/* The first 2 bits represent the number of layers minus 1 */
diff --git a/backend/code16k.c b/backend/code16k.c
index 491806df..f4c7c29a 100644
--- a/backend/code16k.c
+++ b/backend/code16k.c
@@ -229,7 +229,7 @@ int code16k(struct zint_symbol *symbol, unsigned char source[])
 	}
 
 	/* We have a problem with FNC1 in Code Set C to resolve */
-	for(i = 0; i < read; i++) {
+	for(i = 0; i < input_length; i++) {
 		if((set[i] == 'C') && (source[i] == '[')) {
 			int c_count;