diff --git a/notes-utils.c b/notes-utils.c
index 36c1490..325ff3d 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -18,7 +18,7 @@ void create_notes_commit(struct notes_tree *t, struct commit_list *parents,
 		/* Deduce parent commit from t->ref */
 		struct object_id parent_oid;
 		if (!read_ref(t->ref, parent_oid.hash)) {
-			struct commit *parent = lookup_commit(parent_oid.hash);
+			struct commit *parent = lookup_commit(&parent_oid);
 			if (parse_commit(parent))
 				die("Failed to find/parse commit %s", t->ref);
 			commit_list_insert(parent, &parents);