diff --git a/apps/ocsp.c b/apps/ocsp.c
index 6ae5fd11dd2b064a328485d8e45c0c2ebea0700d..6b7e85de36b5214933f3ba6aa35ac5d4278aefb3 100644
--- a/apps/ocsp.c
+++ b/apps/ocsp.c
@@ -1146,6 +1146,7 @@ static char **lookup_serial(CA_DB *db, ASN1_INTEGER *ser)
 	char *itmp, *row[DB_NUMBER],**rrow;
 	for (i = 0; i < DB_NUMBER; i++) row[i] = NULL;
 	bn = ASN1_INTEGER_to_BN(ser,NULL);
+	OPENSSL_assert(bn); /* FIXME: should report an error at this point and abort */
 	if (BN_is_zero(bn))
 		itmp = BUF_strdup("00");
 	else