diff --git a/src/effect/schema/tests.ts b/src/effect/schema/tests.ts
index fe75ca0..d2fa624 100644
--- a/src/effect/schema/tests.ts
+++ b/src/effect/schema/tests.ts
@@ -12,13 +12,12 @@ import { Mutable } from "./class/Mutable"
 //     MobXObservable
 // ) {}
 
-class User extends TaggedClass<User>()("User", {
+class User extends Class<User>("User")({
     id:    S.BigIntFromSelf,
     role:  S.Union(S.Literal("BasicUser"), S.Literal("Admin")),
-}).pipe(
-    Mutable,
-    MobXObservable,
-) {}
+}) {}
+
+const MutableUser = Mutable(User)
 
 const JsonifiableUser = User.pipe(
     Jsonifiable(S.Struct({