diff --git a/src/libosmo-mgcp/mgcp_osmux.c b/src/libosmo-mgcp/mgcp_osmux.c
index 38657ee..72d3b91 100644
--- a/src/libosmo-mgcp/mgcp_osmux.c
+++ b/src/libosmo-mgcp/mgcp_osmux.c
@@ -473,9 +473,10 @@
 		return -1;
 	}
 
-	osmux_xfrm_output_init(&conn->osmux.out,
+	osmux_xfrm_output_init2(&conn->osmux.out,
 			       (conn->osmux.cid * rtp_ssrc_winlen) +
-			       (random() % rtp_ssrc_winlen));
+			        (random() % rtp_ssrc_winlen),
+			       conn->end.codec->payload_type);
 
 	osmux_xfrm_output_set_tx_cb(&conn->osmux.out,
 				    scheduled_from_osmux_tx_rtp_cb, conn);