diff --git a/tsdb/wlog/watcher.go b/tsdb/wlog/watcher.go
index 525515221d..6994d2dd8a 100644
--- a/tsdb/wlog/watcher.go
+++ b/tsdb/wlog/watcher.go
@@ -262,9 +262,6 @@ func (w *Watcher) loop() {
 // Run the watcher, which will tail the WAL until the quit channel is closed
 // or an error case is hit.
 func (w *Watcher) Run() error {
-	var lastSegment int
-	var err error
-
 	// We want to ensure this is false across iterations since
 	// Run will be called again if there was a failure to read the WAL.
 	w.sendSamples = false
@@ -289,21 +286,19 @@ func (w *Watcher) Run() error {
 		return err
 	}
 
-	level.Debug(w.logger).Log("msg", "Tailing WAL", "lastCheckpoint", lastCheckpoint, "checkpointIndex", checkpointIndex, "currentSegment", currentSegment, "lastSegment", lastSegment)
+	level.Debug(w.logger).Log("msg", "Tailing WAL", "lastCheckpoint", lastCheckpoint, "checkpointIndex", checkpointIndex, "currentSegment", currentSegment)
 	for !isClosed(w.quit) {
 		w.currentSegmentMetric.Set(float64(currentSegment))
-		level.Debug(w.logger).Log("msg", "Processing segment", "currentSegment", currentSegment)
 
-		// Reset the value of lastSegment each iteration, this is to avoid having to wait too long for
-		// between reads if we're reading a segment that is not the most recent segment after startup.
-		_, lastSegment, err = w.firstAndLast()
+		// Re-check on each iteration in case a new segment was added,
+		// because watch() will wait for notifications on the last segment.
+		_, lastSegment, err := w.firstAndLast()
 		if err != nil {
 			return fmt.Errorf("wal.Segments: %w", err)
 		}
 		tail := currentSegment >= lastSegment
 
-		// On start, after reading the existing WAL for series records, we have a pointer to what is the latest segment.
-		// On subsequent calls to this function, currentSegment will have been incremented and we should open that segment.
+		level.Debug(w.logger).Log("msg", "Processing segment", "currentSegment", currentSegment, "lastSegment", lastSegment)
 		if err := w.watch(currentSegment, tail); err != nil && !errors.Is(err, ErrIgnorable) {
 			return err
 		}
diff --git a/tsdb/wlog/watcher_test.go b/tsdb/wlog/watcher_test.go
index 871640a7cf..ff006cb817 100644
--- a/tsdb/wlog/watcher_test.go
+++ b/tsdb/wlog/watcher_test.go
@@ -59,46 +59,36 @@ type writeToMock struct {
 	seriesLock              sync.Mutex
 	seriesSegmentIndexes    map[chunks.HeadSeriesRef]int
 
-	// delay reads with a short sleep
+	// If nonzero, delay reads with a short sleep.
 	delay time.Duration
 }
 
 func (wtm *writeToMock) Append(s []record.RefSample) bool {
-	if wtm.delay > 0 {
-		time.Sleep(wtm.delay)
-	}
+	time.Sleep(wtm.delay)
 	wtm.samplesAppended += len(s)
 	return true
 }
 
 func (wtm *writeToMock) AppendExemplars(e []record.RefExemplar) bool {
-	if wtm.delay > 0 {
-		time.Sleep(wtm.delay)
-	}
+	time.Sleep(wtm.delay)
 	wtm.exemplarsAppended += len(e)
 	return true
 }
 
 func (wtm *writeToMock) AppendHistograms(h []record.RefHistogramSample) bool {
-	if wtm.delay > 0 {
-		time.Sleep(wtm.delay)
-	}
+	time.Sleep(wtm.delay)
 	wtm.histogramsAppended += len(h)
 	return true
 }
 
 func (wtm *writeToMock) AppendFloatHistograms(fh []record.RefFloatHistogramSample) bool {
-	if wtm.delay > 0 {
-		time.Sleep(wtm.delay)
-	}
+	time.Sleep(wtm.delay)
 	wtm.floatHistogramsAppended += len(fh)
 	return true
 }
 
 func (wtm *writeToMock) StoreSeries(series []record.RefSeries, index int) {
-	if wtm.delay > 0 {
-		time.Sleep(wtm.delay)
-	}
+	time.Sleep(wtm.delay)
 	wtm.UpdateSeriesSegment(series, index)
 }