diff --git a/src/tests.ts b/src/tests.ts
index 2b5265a..302199c 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -1,45 +1,75 @@
-import { Implements } from "@thilawyn/traitify-ts"
+import { Implements, expression } from "@thilawyn/traitify-ts"
+import { Class } from "type-fest"
 import { z } from "zod"
-import { zodSchemaClass } from "./builders/ZodSchemaClassBuilder"
-import { dejsonify, jsonify } from "./schema/jsonify"
-import { MobXObservableZodSchemaObject } from "./traits/MobXObservableZodSchemaObject"
+import { ZodSchemaObject } from "./traits/ZodSchemaObject"
+import { StaticMembers } from "./util"
 
 
-const exp = zodSchemaClass
-    .schema({
-        schema: z.object({
-            /** User ID */
-            id: z.bigint(),
+// const exp = zodSchemaClass
+//     .schema({
+//         schema: z.object({
+//             /** User ID */
+//             id: z.bigint(),
 
-            /** Username */
-            name: z.string(),
-        }),
+//             /** Username */
+//             name: z.string(),
+//         }),
 
-        schemaWithDefaultValues: s => s.extend({
-            id: s.shape.id.default(-1n),
-        }),
-    })
-    .jsonifiable({
-        jsonifySchema: s => s.extend({
-            id: jsonify.bigint(s.shape.id)
-        }),
+//         schemaWithDefaultValues: s => s.extend({
+//             id: s.shape.id.default(-1n),
+//         }),
+//     })
+//     .jsonifiable({
+//         jsonifySchema: s => s.extend({
+//             id: jsonify.bigint(s.shape.id)
+//         }),
 
-        dejsonifySchema: s => s.extend({
-            id: dejsonify.bigint(s.shape.id)
-        }),
-    })
-    .expresses(MobXObservableZodSchemaObject)
+//         dejsonifySchema: s => s.extend({
+//             id: dejsonify.bigint(s.shape.id)
+//         }),
+//     })
+//     .expresses(MobXObservableZodSchemaObject)
+//     .build()
+
+const schema = z.object({
+    /** User ID */
+    id: z.bigint(),
+
+    /** Username */
+    name: z.string(),
+})
+const schemaWithDefaultsValues = schema.extend({
+    id: schema.shape.id.default(-1n),
+})
+class UserSchemas {
+    static readonly schema = schema
+    static readonly schemaWithDefaultValues = schemaWithDefaultsValues
+
+    constructor(values: z.output<typeof schema>) {
+        Object.assign(this, values)
+    }
+}
+
+const exp = expression
+    .extends(UserSchemas as (
+        Class<UserSchemas & z.output<typeof schema>> &
+        StaticMembers<typeof UserSchemas>
+    ))
+    .expresses(
+        ZodSchemaObject(
+            schema,
+
+            s => s.extend({
+                id: s.shape.id.default(-1n),
+            }),
+        )
+    )
     .build()
 
+
 @exp.staticImplements
 class User extends exp.extends implements Implements<typeof exp> {}
 
-const test = User.schema.extend({
-    prout: z.string()
-}).merge(
-    User.schemaWithDefaultValues
-)
-
 const inst = User.create({ id: 1n, name: "User" })
 // console.log(inst.name)
 const instEffect = User.createEffect({ id: 1n, name: "User" })
diff --git a/src/traits/ZodSchemaObject.ts b/src/traits/ZodSchemaObject.ts
index 20d5fba..b39d34c 100644
--- a/src/traits/ZodSchemaObject.ts
+++ b/src/traits/ZodSchemaObject.ts
@@ -36,23 +36,19 @@ export const ZodSchemaObject = <
         static readonly schemaWithDefaultsValues = schemaWithDefaultValues(schema)
 
         static instantiationSchema<
-            Instance extends Values
+            Self     extends StaticMembers<ImplStaticThis<typeof ZodSchemaObject>>,
+            Instance extends Values,
         >(
-            this: (
-                Class<Instance, [values: Values]> &
-                StaticMembers<ImplStaticThis<typeof ZodSchemaObject>>
-            )
+            this: Class<Instance, [values: Values]> & Self
         ) {
             return this.schema.transform(values => new this(values))
         }
 
         static instantiationSchemaWithDefaultValues<
-            Instance extends Values
+            Self     extends StaticMembers<ImplStaticThis<typeof ZodSchemaObject>>,
+            Instance extends Values,
         >(
-            this: (
-                Class<Instance, [values: Values]> &
-                StaticMembers<ImplStaticThis<typeof ZodSchemaObject>>
-            )
+            this: Class<Instance, [values: Values]> & Self
         ) {
             return this.schema.transform(values => new this(values))
         }
@@ -67,7 +63,7 @@ export const ZodSchemaObject = <
             ),
             ...[values, params]: NewZodSchemaInstanceArgs<PartialValues>
         ) {
-            return this.instantiationSchema().parse(values, params)
+            return this.instantiationSchemaWithDefaultValues().parse(values, params)
         }
     })
     .build()