diff --git a/src/Schema/MobX/ObservableClass.ts b/src/Schema/MobX/ObservableClass.ts
index e723f12..61243c7 100644
--- a/src/Schema/MobX/ObservableClass.ts
+++ b/src/Schema/MobX/ObservableClass.ts
@@ -8,24 +8,19 @@ interface ObservableClassSelf {
     readonly fields: { readonly [K in keyof Schema.Struct.Fields]: Schema.Struct.Fields[K] }
 }
 
-export const ObservableClass = <Self extends ObservableClassSelf>(
-    self:      Self,
-    options?:  Omit<CreateObservableOptions, "proxy">,
-) =>
-    class Observable extends self {
-        declare ["constructor"]: typeof Observable
+interface ObservableClassOptions extends Omit<CreateObservableOptions, "proxy"> {}
 
-        constructor(...args: any[]) {
-            super(...args)
+export const ObservableClass = (options?: ObservableClassOptions) =>
+    <Self extends ObservableClassSelf>(self: Self) =>
+        class Observable extends self {
+            declare ["constructor"]: typeof Observable
 
-            makeObservable(this,
-                mapValues(this.constructor.fields, () => observable),
-                options,
-            )
-        }
-    } as Self
+            constructor(...args: any[]) {
+                super(...args)
 
-export const ObservableClassDual: {
-    <Self extends ObservableClassSelf>(options?: Omit<CreateObservableOptions, "proxy">): (self: Self) => Self
-    <Self extends ObservableClassSelf>(self: Self, options?: Omit<CreateObservableOptions, "proxy">): Self
-} = () => {}
+                makeObservable(this,
+                    mapValues(this.constructor.fields, () => observable),
+                    options,
+                )
+            }
+        } as Self
diff --git a/src/tests.ts b/src/tests.ts
index f1adbc7..e23104f 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -22,7 +22,7 @@ class User extends MutableTaggedClass<User>()("User", {
     id:    S.BigIntFromSelf,
     role:  S.Union(S.Literal("BasicUser"), S.Literal("Admin")),
 }).pipe(
-    ObservableClass
+    ObservableClass()
 ) {}
 
 const JsonifiableUser = User.pipe(