diff --git a/src/tests.ts b/src/tests.ts
index 9b096a8..0cc019f 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -1,4 +1,5 @@
-import { expresses, trait } from "."
+import { Simplify } from "type-fest"
+import { TraitAbstractMembers, TraitImpl, TraitInstance, expresses, trait } from "."
 
 
 const PrintsHelloOnNew = trait()(Super =>
@@ -21,6 +22,10 @@ const Identifiable = <ID>() => (
 )
 
 
+type Test = Simplify<TraitImpl<ReturnType<typeof Identifiable<bigint>>>>
+
 const exp = expresses(Identifiable<bigint>())
 
-class User implements typeof exp.implements()
+class User implements ReturnType<typeof exp.implements> {
+    id: bigint = -1n
+}