diff --git a/src/x509.c b/src/x509.c
index 2cdd0be9d..e711e1c5a 100644
--- a/src/x509.c
+++ b/src/x509.c
@@ -7559,7 +7559,7 @@ int wc_GeneratePreTBS(DecodedCert* cert, byte *der, int derSz) {
         /* Remove the altsigval extension. */
         XFREE(x->altSigValDer, x->heap, DYNAMIC_TYPE_X509_EXT);
         x->altSigValDer = NULL;
-        x->altSigValDer = 0;
+        x->altSigValLen = 0;
         /* Remove sigOID so it won't be encoded. */
         x->sigOID = 0;
         /* We now have a PreTBS. Encode it. */