diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index 3a7f049247..52df94439d 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -1552,7 +1552,7 @@ get_object_address_opf_member(ObjectType objtype,
 	ObjectAddress address;
 	ListCell   *cell;
 	List	   *copy;
-	char	   *typenames[2];
+	char	   *typenames[2] = {NULL, NULL};
 	Oid			typeoids[2];
 	int			membernum;
 	int			i;
@@ -1581,6 +1581,8 @@ get_object_address_opf_member(ObjectType objtype,
 			break;
 	}
 
+	Assert(typenames[0] != NULL && typenames[1] != NULL);
+
 	switch (objtype)
 	{
 		case OBJECT_AMOP: