diff --git a/storage/local/series.go b/storage/local/series.go
index fe30e9f77c..f58371746a 100644
--- a/storage/local/series.go
+++ b/storage/local/series.go
@@ -255,7 +255,7 @@ func (s *memorySeries) maybeCloseHeadChunk(timeout time.Duration) (bool, error)
 	if s.headChunkClosed {
 		return false, nil
 	}
-	if time.Now().Sub(s.lastTime.Time()) > timeout {
+	if time.Since(s.lastTime.Time()) > timeout {
 		s.headChunkClosed = true
 		// Since we cannot modify the head chunk from now on, we
 		// don't need to bother with cloning anymore.