diff --git a/src/tests.ts b/src/tests.ts
index e23104f..de20458 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -1,5 +1,5 @@
 import { Schema as S } from "@effect/schema"
-import { reaction, runInAction } from "mobx"
+import { computed, makeObservable, reaction, runInAction } from "mobx"
 import type { Simplify } from "type-fest"
 import { MutableTaggedClass, toJsonifiable } from "./Schema"
 import { ObservableClass } from "./Schema/MobX"
@@ -18,12 +18,24 @@ type TestB = {
 type Merged = Simplify<ExtendAll<[TestA, TestB]>>
 
 
-class User extends MutableTaggedClass<User>()("User", {
+
+const UserSchema = MutableTaggedClass<User>()("User", {
     id:    S.BigIntFromSelf,
     role:  S.Union(S.Literal("BasicUser"), S.Literal("Admin")),
 }).pipe(
     ObservableClass()
-) {}
+)
+
+class User extends UserSchema {
+    constructor(...args: ConstructorParameters<typeof UserSchema>) {
+        super(...args)
+        makeObservable(this, { idAsString: computed })
+    }
+
+    get idAsString() {
+        return this.id.toString()
+    }
+}
 
 const JsonifiableUser = User.pipe(
     toJsonifiable(S.Struct({