diff --git a/src/trau/osmo_ortp.c b/src/trau/osmo_ortp.c
index 141065e..4e9df56 100644
--- a/src/trau/osmo_ortp.c
+++ b/src/trau/osmo_ortp.c
@@ -467,9 +467,9 @@
 		return -ENOMEM;
 
 	rtp_set_markbit(mblk, marker);
+	rs->tx_timestamp += duration;
 	rc = rtp_session_sendm_with_ts(rs->sess, mblk,
 				       rs->tx_timestamp);
-	rs->tx_timestamp += duration;
 	if (rc < 0) {
 		/* no need to free() the mblk, as rtp_session_rtp_send()
 		 * unconditionally free()s the mblk even in case of