diff --git a/tools/cache/reflector.go b/tools/cache/reflector.go
index c43b7fc5..a629fd4e 100644
--- a/tools/cache/reflector.go
+++ b/tools/cache/reflector.go
@@ -363,7 +363,7 @@ loop:
 		}
 	}
 
-	watchDuration := r.clock.Now().Sub(start)
+	watchDuration := r.clock.Since(start)
 	if watchDuration < 1*time.Second && eventCount == 0 {
 		return fmt.Errorf("very short watch: %s: Unexpected watch close - watch lasted less than a second and no items received", r.name)
 	}
diff --git a/util/flowcontrol/backoff.go b/util/flowcontrol/backoff.go
index b7cb70ea..39cd72f9 100644
--- a/util/flowcontrol/backoff.go
+++ b/util/flowcontrol/backoff.go
@@ -99,7 +99,7 @@ func (p *Backoff) IsInBackOffSince(id string, eventTime time.Time) bool {
 	if hasExpired(eventTime, entry.lastUpdate, p.maxDuration) {
 		return false
 	}
-	return p.Clock.Now().Sub(eventTime) < entry.backoff
+	return p.Clock.Since(eventTime) < entry.backoff
 }
 
 // Returns True if time since lastupdate is less than the current backoff window.
diff --git a/util/flowcontrol/backoff_test.go b/util/flowcontrol/backoff_test.go
index b14ab341..4d061d54 100644
--- a/util/flowcontrol/backoff_test.go
+++ b/util/flowcontrol/backoff_test.go
@@ -114,14 +114,14 @@ func TestBackoffGC(t *testing.T) {
 	b.GC()
 	_, found := b.perItemBackoff[id]
 	if !found {
-		t.Errorf("expected GC to skip entry, elapsed time=%s maxDuration=%s", tc.Now().Sub(lastUpdate), maxDuration)
+		t.Errorf("expected GC to skip entry, elapsed time=%s maxDuration=%s", tc.Since(lastUpdate), maxDuration)
 	}
 
 	tc.Step(maxDuration + step)
 	b.GC()
 	r, found := b.perItemBackoff[id]
 	if found {
-		t.Errorf("expected GC of entry after %s got entry %v", tc.Now().Sub(lastUpdate), r)
+		t.Errorf("expected GC of entry after %s got entry %v", tc.Since(lastUpdate), r)
 	}
 }