if (dryrun)
                hash_sha1_file(buffer.buf, buffer.len, tree_type, it->sha1);
-       else
-               write_sha1_file(buffer.buf, buffer.len, tree_type, it->sha1);
+       else if (write_sha1_file(buffer.buf, buffer.len, tree_type, it->sha1)) {
+               strbuf_release(&buffer);
+               return -1;
+       }
+
        strbuf_release(&buffer);
        it->entry_count = i;
 #if DEBUG