diff --git a/conn.go b/conn.go
index 8fed8df..df624eb 100644
--- a/conn.go
+++ b/conn.go
@@ -24,23 +24,24 @@ type localTrackAction struct {
 }
 
 type upTrack struct {
-	track                *webrtc.Track
-	label                string
-	rate                 *estimator.Estimator
-	cache                *packetcache.Cache
-	jitter               *jitter.Estimator
-	maxBitrate           uint64
-	lastPLI              uint64
-	lastFIR              uint64
-	firSeqno             uint32
-	lastSenderReport     uint32
-	lastSenderReportTime uint32
+	track      *webrtc.Track
+	label      string
+	rate       *estimator.Estimator
+	cache      *packetcache.Cache
+	jitter     *jitter.Estimator
+	maxBitrate uint64
+	lastPLI    uint64
+	lastFIR    uint64
+	firSeqno   uint32
 
 	localCh    chan localTrackAction // signals that local has changed
 	writerDone chan struct{}         // closed when the loop dies
 
-	mu    sync.Mutex
-	local []downTrack
+	mu        sync.Mutex
+	local     []downTrack
+	srTime    uint64
+	srNTPTime uint64
+	srRTPTime uint32
 }
 
 func (up *upTrack) notifyLocal(add bool, track downTrack) {
diff --git a/webclient.go b/webclient.go
index 6be50f7..7922ba1 100644
--- a/webclient.go
+++ b/webclient.go
@@ -558,10 +558,11 @@ func rtcpUpListener(conn *upConnection, track *upTrack, r *webrtc.RTPReceiver) {
 		for _, p := range ps {
 			switch p := p.(type) {
 			case *rtcp.SenderReport:
-				atomic.StoreUint32(&track.lastSenderReport,
-					uint32(p.NTPTime>>16))
-				atomic.StoreUint32(&track.lastSenderReportTime,
-					uint32(mono.Now(0x10000)))
+				track.mu.Lock()
+				track.srTime = mono.Now(0x10000)
+				track.srNTPTime = p.NTPTime
+				track.srRTPTime = p.RTPTime
+				track.mu.Unlock()
 			case *rtcp.SourceDescription:
 			}
 		}
@@ -573,7 +574,7 @@ func sendRR(conn *upConnection) error {
 		return nil
 	}
 
-	now := uint32(mono.Now(0x10000))
+	now := mono.Now(0x10000)
 
 	reports := make([]rtcp.ReceptionReport, 0, len(conn.tracks))
 	for _, t := range conn.tracks {
@@ -584,10 +585,15 @@ func sendRR(conn *upConnection) error {
 		if lost >= expected {
 			lost = expected - 1
 		}
-		lastSR := atomic.LoadUint32(&t.lastSenderReport)
-		var delay uint32
-		if lastSR != 0 {
-			delay = now - atomic.LoadUint32(&t.lastSenderReportTime)
+
+		t.mu.Lock()
+		srTime := t.srTime
+		srNTPTime := t.srNTPTime
+		t.mu.Unlock()
+
+		var delay uint64
+		if srNTPTime != 0 {
+			delay = now - srTime
 		}
 
 		reports = append(reports, rtcp.ReceptionReport{
@@ -596,8 +602,8 @@ func sendRR(conn *upConnection) error {
 			TotalLost:          totalLost,
 			LastSequenceNumber: eseqno,
 			Jitter:             t.jitter.Jitter(),
-			LastSenderReport:   lastSR,
-			Delay:              delay,
+			LastSenderReport:   uint32(srNTPTime >> 16),
+			Delay:              uint32(delay),
 		})
 	}