if ((mod(msg_seqno(buf_msg(l_ptr->last_out)) -
msg_seqno(buf_msg(l_ptr->first_out)))
!= (l_ptr->out_queue_size - 1))
- || (l_ptr->last_out->next != 0)) {
+ || (l_ptr->last_out->next != NULL)) {
tipc_printf(buf, "\nSend queue inconsistency\n");
tipc_printf(buf, "first_out= %x ", l_ptr->first_out);
tipc_printf(buf, "next_out= %x ", l_ptr->next_out);