diff --git a/tsdb/wal/wal.go b/tsdb/wal/wal.go
index 510326b881..bb57975ad6 100644
--- a/tsdb/wal/wal.go
+++ b/tsdb/wal/wal.go
@@ -190,7 +190,7 @@ type walMetrics struct {
 	writesFailed    prometheus.Counter
 }
 
-func newWALMetrics(w *WAL, r prometheus.Registerer) *walMetrics {
+func newWALMetrics(r prometheus.Registerer) *walMetrics {
 	m := &walMetrics{}
 
 	m.fsyncDuration = prometheus.NewSummary(prometheus.SummaryOpts{
@@ -264,7 +264,7 @@ func NewSize(logger log.Logger, reg prometheus.Registerer, dir string, segmentSi
 		stopc:       make(chan chan struct{}),
 		compress:    compress,
 	}
-	w.metrics = newWALMetrics(w, reg)
+	w.metrics = newWALMetrics(reg)
 
 	_, last, err := w.Segments()
 	if err != nil {