diff --git a/util/cache/none.go b/util/cache/none.go
index e3e53e0b4..c4073e0d9 100644
--- a/util/cache/none.go
+++ b/util/cache/none.go
@@ -8,6 +8,8 @@
 // It is safe for concurrent use if the underlying FillFunc is.
 type None[K comparable, V any] struct{}
 
+var _ Cache[int, int] = None[int, int]{}
+
 // Get always calls the provided FillFunc and returns what it does.
 func (c None[K, V]) Get(_ K, f FillFunc[V]) (V, error) {
 	v, _, e := f()
@@ -15,4 +17,7 @@ func (c None[K, V]) Get(_ K, f FillFunc[V]) (V, error) {
 }
 
 // Forget implements Cache.
-func (c None[K, V]) Forget() {}
+func (None[K, V]) Forget(K) {}
+
+// Empty implements Cache.
+func (None[K, V]) Empty() {}
diff --git a/util/cache/single.go b/util/cache/single.go
index 5b378cc15..6b9ac2c11 100644
--- a/util/cache/single.go
+++ b/util/cache/single.go
@@ -25,6 +25,8 @@ type Single[K comparable, V any] struct {
 	ServeExpired bool
 }
 
+var _ Cache[int, int] = (*Single[int, int])(nil)
+
 // Get will return the cached value, if any, or fill the cache by calling f and
 // return the corresponding value. If f returns an error and c.ServeExpired is
 // true, then a previous expired value can be returned with no error.