diff --git a/langex/classes/singleton.py b/langex/classes/singleton.py
index 45ba600..bf0adbe 100644
--- a/langex/classes/singleton.py
+++ b/langex/classes/singleton.py
@@ -1,17 +1,17 @@
-class Singleton:
-  def __init__(self, cls):
-    self.cls = cls
-    self.instance = None
+from langex.classes.class_meta import ClassMeta
 
-  def __call__(self, *args, **kwargs):
-    if self.instance is None:
-      self.instance = self.cls(*args, **kwargs)
+def Singleton(cls):
+  instance = ClassMeta(cls).use_primitive()()
 
-    return self.instance
+  class Wrapper():
+    def __call__(self):
+      return instance
 
-  def __getattr__(self, name):
-    if self.instance is None:
-      self.instance = self.cls()
+    def __getattr__(self, name):
+      return getattr(instance, name)
 
-    return getattr(self.instance, name)
+    def __setattr__(self, name, value):
+      return setattr(instance, name, value)
+
+  return Wrapper()
 
diff --git a/langex/functions/function_meta.py b/langex/functions/function_meta.py
index 38263ff..b3f2d45 100644
--- a/langex/functions/function_meta.py
+++ b/langex/functions/function_meta.py
@@ -32,12 +32,22 @@ def __init__(self, func):
     self.bounded = self.check_class_bound()
     self.signature = Signature(self.qual)
     self.is_abstract = False
+    self._inject_mimic(func)
     self._inject()
 
   def _inject(self):
     setattr(self, LANGEX.MARKER, True)
     setattr(self, LANGEX.FUNC_META, self)
 
+  def _inject_mimic(self, func):
+    self.__code__ = self.func.__code__
+    self.__defaults__ = self.func.__defaults__
+    self.__kwdefaults__ = self.func.__kwdefaults__
+    self.__annotations__ = self.func.__annotations__
+    self.__doc__ = self.func.__doc__
+    self.__qualname__ = self.func.__qualname__
+    self.__name__ = self.func.__name__
+
   def check_class_bound(self):
     parts = self.qual.split(".")
 
diff --git a/tests/classes/test_singleton.py b/tests/classes/test_singleton.py
index 17b27d2..3cb3ee2 100644
--- a/tests/classes/test_singleton.py
+++ b/tests/classes/test_singleton.py
@@ -1,4 +1,6 @@
 from langex.core.classes import singleton
+from langex.core.errors import ValidationError
+from langex.core.functions import autosig
 from langex.core.testing import discover_test, expects
 
 @singleton
@@ -11,12 +13,18 @@ def next_id(self):
 
     return self.value
 
+  @autosig
+  def next_id_with_prefix(self, prefix: str) -> str:
+    return f"{prefix}_{self.next_id()}"
+
 @discover_test
 def test_singleton():
   id_gen1 = IdGenerator()
   id_gen2 = IdGenerator()
-  (id_gen1.next_id           ) @expects (1)
-  (id_gen1.next_id           ) @expects (2)
-  (id_gen2.next_id           ) @expects (3)
-  (lambda: id_gen1 is id_gen2) @expects (True)
+  (id_gen1.next_id                          ) @expects (1)
+  (id_gen1.next_id                          ) @expects (2)
+  (id_gen2.next_id                          ) @expects (3)
+  (lambda: id_gen1 is id_gen2               ) @expects (True)
+  (lambda: id_gen1.next_id_with_prefix(0)   ) @expects (ValidationError)
+  (lambda: id_gen1.next_id_with_prefix("ID")) @expects ("ID_4")