diff --git a/src/effect/EffectSchemaTraitExpressionBuilder.ts b/src/effect/EffectSchemaTraitExpressionBuilder.ts
index 50a4110..18e6be3 100644
--- a/src/effect/EffectSchemaTraitExpressionBuilder.ts
+++ b/src/effect/EffectSchemaTraitExpressionBuilder.ts
@@ -42,7 +42,7 @@ export class EffectSchemaInitialTraitExpressionBuilder {
 
     extends<
         Super     extends StaticMembers<S.Class<Self, Fields, I, R, C, Inherited, Proto>>,
-        Self,
+        Self      extends object,
         Fields    extends S.Struct.Fields,
         I, R, C,
         Inherited extends object,
@@ -56,15 +56,7 @@ export class EffectSchemaInitialTraitExpressionBuilder {
         annotations?:  S.Annotations.Schema<unknown>,
     ) {
         return new EffectSchemaTraitExpressionBuilder(
-            superclass.extend<unknown>(identifier)(fields, annotations) as S.Class<
-                unknown,
-                Fields & NewFields,
-                I & S.Struct.Encoded<NewFields>,
-                R | S.Struct.Context<NewFields>,
-                C & S.Struct.Constructor<NewFields>,
-                Self,
-                Proto
-            >,
+            superclass.extend<unknown>(identifier)(fields, annotations),
 
             {} as Simplify<
                 Omit<Super,
diff --git a/src/effect/tests.ts b/src/effect/tests.ts
index a241123..aa33f91 100644
--- a/src/effect/tests.ts
+++ b/src/effect/tests.ts
@@ -54,8 +54,6 @@ const adminExp = effectSchemaExpression
     // .immutable()
     .build()
 
-type T = InspectSchemaClass<typeof adminExp.superclass>
-
 @adminExp.staticImplements
 export class Admin extends adminExp.extends<Admin>() implements Implements<typeof adminExp> {
 }