diff --git a/src/rtp/sess.c b/src/rtp/sess.c
index 4bec3ef..ee454c1 100644
--- a/src/rtp/sess.c
+++ b/src/rtp/sess.c
@@ -563,12 +563,12 @@ void rtcp_sess_rx_rtp(struct rtcp_sess *sess, uint16_t seq, uint32_t ts,
 
 	if (sess->srate_rx) {
 
-		uint32_t ts_arrive;
+		uint64_t ts_arrive;
 
 		/* Convert from wall-clock time to timestamp units */
-		ts_arrive = (uint32_t)(tmr_jiffies()) * sess->srate_rx / 1000;
+		ts_arrive = tmr_jiffies() * sess->srate_rx / 1000;
 
-		source_calc_jitter(mbr->s, ts, ts_arrive);
+		source_calc_jitter(mbr->s, ts, (uint32_t)ts_arrive);
 	}
 
 	mbr->s->rtp_rx_bytes += payload_size;
diff --git a/src/rtp/source.c b/src/rtp/source.c
index 71d32f0..f87f177 100644
--- a/src/rtp/source.c
+++ b/src/rtp/source.c
@@ -117,10 +117,12 @@ void source_calc_jitter(struct rtp_source *s, uint32_t rtp_ts,
 	const int transit = arrival - rtp_ts;
 	int d = transit - s->transit;
 
-	s->transit = transit;
-
-	if (!s->rtp_rx_bytes)
+	if (!s->transit) {
+		s->transit = transit;
 		return;
+	}
+
+	s->transit = transit;
 
 	if (d < 0)
 		d = -d;