unsigned char *sha1)
 {
        if (commit->parents)
-               diff_tree_sha1(commit->parents->item->object.sha1,
-                              commit->object.sha1, "", options);
+               diff_tree_sha1(commit->parents->item->object.oid.hash,
+                              commit->object.oid.hash, "", options);
        else
-               diff_root_tree_sha1(commit->object.sha1, "", options);
+               diff_root_tree_sha1(commit->object.oid.hash, "", options);
        diffcore_std(options);
        return diff_flush_patch_id(options, sha1);
 }