(!hashcmp(cb.nsha1, sha1) ||
             /* perhaps sha1 is a tag, try to dereference to a commit */
             ((commit = lookup_commit_reference_gently(sha1, 1)) != NULL &&
-             !hashcmp(cb.nsha1, commit->object.sha1)))) {
+             !hashcmp(cb.nsha1, commit->object.oid.hash)))) {
                const char *from = ref;
                if (!skip_prefix(from, "refs/tags/", &from))
                        skip_prefix(from, "refs/remotes/", &from);