diff --git a/wolfcrypt/src/asn.c b/wolfcrypt/src/asn.c
index 9d2e7f66b..e98816582 100755
--- a/wolfcrypt/src/asn.c
+++ b/wolfcrypt/src/asn.c
@@ -2014,7 +2014,7 @@ WOLFSSL_LOCAL int GetAlgoId(const byte* input, word32* inOutIdx, word32* oid,
         return ASN_OBJECT_ID_E;
 
     /* could have NULL tag and 0 terminator, but may not */
-    if (input[idx] == ASN_TAG_NULL) {
+    if (idx < maxIdx && input[idx] == ASN_TAG_NULL) {
         ret = GetASNNull(input, &idx, maxIdx);
         if (ret != 0)
             return ret;