diff --git a/lib/ratp.c b/lib/ratp.c
index 1901cc8..ce30223 100644
--- a/lib/ratp.c
+++ b/lib/ratp.c
@@ -1109,6 +1109,8 @@
 
 	ratp_state_change(ri, RATP_STATE_LAST_ACK);
 
+	ri->sn_received = ratp_sn(hdr);
+
 	return 1;
 }