diff --git a/lib/asn1/der_get.c b/lib/asn1/der_get.c
index 1f9b5d72d..00efa76c1 100644
--- a/lib/asn1/der_get.c
+++ b/lib/asn1/der_get.c
@@ -145,10 +145,9 @@ der_get_general_string (const unsigned char *p, size_t len,
 	 * an strings in the NEED_PREAUTH case that includes a
 	 * trailing NUL.
 	 */
-	len = p1 - p;
-	while (*p1 == '\0' && p1 - p < len)
+	while (p1 - p < len && *p1 == '\0')
 	    p1++;
-	if (p1 - p != len + 1)
+       if (p1 - p != len)
 	    return ASN1_BAD_CHARACTER;
     }
     if (len > len + 1)