struct strbuf buf = STRBUF_INIT;
 
        printf(_("HEAD is now at %s"),
-               find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
+               find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 
        pp_commit_easy(CMIT_FMT_ONELINE, commit, &buf);
        if (buf.len > 0)
        unborn = !strcmp(rev, "HEAD") && get_oid("HEAD", &oid);
        if (unborn) {
                /* reset on unborn branch: treat as reset to empty tree */
-               hashcpy(oid.hash, EMPTY_TREE_SHA1_BIN);
+               oidcpy(&oid, the_hash_algo->empty_tree);
        } else if (!pathspec.nr) {
                struct commit *commit;
                if (get_oid_committish(rev, &oid))