diff --git a/pkg/metrics/writecache.go b/pkg/metrics/writecache.go
index a20c3ca6..67b9d8ca 100644
--- a/pkg/metrics/writecache.go
+++ b/pkg/metrics/writecache.go
@@ -167,7 +167,7 @@ func setWriteCacheDuration(m *prometheus.HistogramVec, shardID string, success b
 			wcSuccess: fmt.Sprintf("%v", success),
 			wcStorage: storageType,
 		},
-	).Observe(float64(d))
+	).Observe(d.Seconds())
 }
 
 func newWCMethodDurationCounter(method string) *prometheus.HistogramVec {