diff --git a/storage/metric/operation.go b/storage/metric/operation.go
index 9c3408c0d7..595cfaf192 100644
--- a/storage/metric/operation.go
+++ b/storage/metric/operation.go
@@ -111,14 +111,14 @@ func extractValuesAroundTime(t time.Time, in model.Values) (out model.Values) {
 		if in[i].Timestamp.Equal(t) && len(in) > i+1 {
 			// We hit exactly the current sample time. Very unlikely in practice.
 			// Return only the current sample.
-			out = append(out, in[i])
+			out = in[i : i+1]
 		} else {
 			if i == 0 {
 				// We hit before the first sample time. Return only the first sample.
-				out = append(out, in[0:1]...)
+				out = in[0:1]
 			} else {
 				// We hit between two samples. Return both surrounding samples.
-				out = append(out, in[i-1:i+1]...)
+				out = in[i-1 : i+1]
 			}
 		}
 	}