diff --git a/lib/asn1/der_format.c b/lib/asn1/der_format.c
index d4f40a256..e5b04bd86 100644
--- a/lib/asn1/der_format.c
+++ b/lib/asn1/der_format.c
@@ -74,7 +74,7 @@ der_parse_hex_heim_integer (const char *p, heim_integer *data)
 
     {
 	unsigned char *q = data->data;
-	while(*q == 0 && len > 0) {
+	while(len > 0 && *q == 0) {
 	    q++;
 	    len--;
 	}