diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index a92e59c889..8f6b37351e 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -2506,7 +2506,8 @@ static int iax2_transmit(struct iax_frame *fr)
 	AST_LIST_INSERT_TAIL(&queue, fr, list);
 	AST_LIST_UNLOCK(&queue);
 	/* Wake up the network and scheduler thread */
-	pthread_kill(netthreadid, SIGURG);
+	if (netthreadid != AST_PTHREADT_NULL)
+		pthread_kill(netthreadid, SIGURG);
 	signal_condition(&sched_lock, &sched_cond);
 	return 0;
 }