diff --git a/storage/metric/test_helper.go b/storage/metric/test_helper.go
index 91885af2c1..6bafbf3634 100644
--- a/storage/metric/test_helper.go
+++ b/storage/metric/test_helper.go
@@ -24,7 +24,7 @@ import (
 )
 
 var (
-	testInstant = time.Now()
+	testInstant = time.Time{}
 )
 
 func testAppendSample(p MetricPersistence, s model.Sample, t test.Tester) {