ASSERT(packet->empty());                                // shouldn't happen

    ByteBuffer buf(2 + 4 + (m_outOfRangeGUIDs.empty() ? 0 : 1 + 4 + 9 * m_outOfRangeGUIDs.size()) + m_data.wpos());

    buf << uint16(m_map);
    buf << uint32((!m_outOfRangeGUIDs.empty() ? m_blockCount + 1 : m_blockCount));

    if (!m_outOfRangeGUIDs.empty())
    {
        buf << uint8(UPDATETYPE_OUT_OF_RANGE_OBJECTS);
        buf << uint32(m_outOfRangeGUIDs.size());

        for (std::set<uint64>::const_iterator i = m_outOfRangeGUIDs.begin(); i != m_outOfRangeGUIDs.end(); ++i)
            buf.appendPackGUID(*i);
    }

    buf.append(m_data);

    packet->append(buf);
    packet->SetOpcode(SMSG_UPDATE_OBJECT);

    return true;