diff --git a/pjsip/src/pjsip/sip_transaction.c b/pjsip/src/pjsip/sip_transaction.c
index c5c1ada3c..960f1fc0d 100644
--- a/pjsip/src/pjsip/sip_transaction.c
+++ b/pjsip/src/pjsip/sip_transaction.c
@@ -1952,7 +1952,7 @@ static void send_msg_callback( pjsip_send_state *send_state,
             tsx_update_transport(tsx, send_state->cur_transport);
 
             /* Update remote address. */
-		pj_assert(tdata->dest_info.cur_addr < _countof(tdata->dest_info.addr.entry));
+		pj_assert(tdata->dest_info.cur_addr < (sizeof(tdata->dest_info.addr.entry)/sizeof(tdata->dest_info.addr.entry[0])));
             tsx->addr_len = tdata->dest_info.addr.entry[tdata->dest_info.cur_addr].addr_len;
             pj_memcpy(&tsx->addr, 
                       &tdata->dest_info.addr.entry[tdata->dest_info.cur_addr].addr,