diff --git a/qlog/qlog.go b/qlog/qlog.go
index 678d3fcd1..2f1f3933d 100644
--- a/qlog/qlog.go
+++ b/qlog/qlog.go
@@ -327,8 +327,8 @@ func (t *tracer) DroppedEncryptionLevel(encLevel protocol.EncryptionLevel) {
 }
 
 func (t *tracer) SetLossTimer(tt TimerType, encLevel protocol.EncryptionLevel, timeout time.Time) {
-	now := time.Now()
 	t.mutex.Lock()
+	now := time.Now()
 	t.recordEvent(now, &eventLossTimerSet{
 		TimerType: tt,
 		EncLevel:  encLevel,