{
        while (targets--) {
                free(target[targets]);
-               if (write_ref[targets])
+               if (write_ref && write_ref[targets])
                        free((char *) write_ref[targets]);
        }
 }
        track_object_refs = 0;
 
        for (i = 0; i < targets; i++) {
-               if (!write_ref[i])
+               if (!write_ref || !write_ref[i])
                        continue;
 
                lock[i] = lock_ref_sha1(write_ref[i], NULL, 0);
                msg = NULL;
        }
        for (i = 0; i < targets; i++) {
-               if (!write_ref[i])
+               if (!write_ref || !write_ref[i])
                        continue;
                ret = write_ref_sha1(lock[i], &sha1[20 * i], msg ? msg : "fetch (unknown)");
                lock[i] = NULL;