diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 5b5ad93..ba085af 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -4054,6 +4054,14 @@ static int retrans_pkt(const void *data)
 
 			/* For non-invites, a maximum of 4 secs */
 			siptimer_a = pkt->timer_t1 * pkt->timer_a;	/* Double each time */
+			if (siptimer_a < pkt->timer_t1 * (pkt->timer_a / 2)) {
+				/*
+				 * We had an integer overflow.
+				 * Calculate previous timeout time instead.
+				 */
+				pkt->timer_a = pkt->timer_a / 2;
+				siptimer_a = pkt->timer_t1 * pkt->timer_a;
+			}
 			if (pkt->method != SIP_INVITE && siptimer_a > 4000) {
 				siptimer_a = 4000;
 			}