diff --git a/entc/entc.go b/entc/entc.go
index 4161ab8d1..c7cf33a63 100644
--- a/entc/entc.go
+++ b/entc/entc.go
@@ -253,7 +253,7 @@ type DefaultExtension struct{}
 func (DefaultExtension) Hooks() []gen.Hook { return nil }
 
 // Annotations of the extensions.
-func (DefaultExtension) Annotations() gen.Annotations { return nil }
+func (DefaultExtension) Annotations() []Annotation { return nil }
 
 // Templates of the extensions.
 func (DefaultExtension) Templates() []*gen.Template { return nil }
@@ -261,6 +261,8 @@ func (DefaultExtension) Templates() []*gen.Template { return nil }
 // Options of the extensions.
 func (DefaultExtension) Options() []Option { return nil }
 
+var _ Extension = (*DefaultExtension)(nil)
+
 // templateOption ensures the template instantiate
 // once for config and execute the given Option.
 func templateOption(next func(t *gen.Template) (*gen.Template, error)) Option {