diff --git a/ikcp.c b/ikcp.c
index 7ae9921..1a9e0b1 100644
--- a/ikcp.c
+++ b/ikcp.c
@@ -551,7 +551,7 @@ static void ikcp_update_ack(ikcpcb *kcp, IINT32 rtt)
 		kcp->rx_srtt = (7 * kcp->rx_srtt + rtt) / 8;
 		if (kcp->rx_srtt < 1) kcp->rx_srtt = 1;
 	}
-	rto = kcp->rx_srtt + _imax_(1, 4 * kcp->rx_rttval);
+	rto = kcp->rx_srtt + _imax_(kcp->interval, 4 * kcp->rx_rttval);
 	kcp->rx_rto = _ibound_(kcp->rx_minrto, rto, IKCP_RTO_MAX);
 }