{
const struct lacp_pdu *pdu;
- pdu = ofpbuf_at(b, (uint8_t *)b->l3 - (uint8_t *)b->data, LACP_PDU_LEN);
+ pdu = ofpbuf_at(b, (uint8_t *)ofpbuf_l3(b) - (uint8_t *)ofpbuf_data(b),
+ LACP_PDU_LEN);
if (pdu && pdu->subtype == 1
&& pdu->actor_type == 1 && pdu->actor_len == 20