diff --git a/django/db/models/base.py b/django/db/models/base.py
index 47c6934..8aec8ed 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -82,9 +82,6 @@ class ModelBase(type):
         return get_model(new_class._meta.app_label, name, False)
 
     def add_to_class(cls, name, value):
-        if name == 'Admin':
-            assert type(value) == types.ClassType, "%r attribute of %s model must be a class, not a %s object" % (name, cls.__name__, type(value))
-            value = AdminOptions(**dict([(k, v) for k, v in value.__dict__.items() if not k.startswith('_')]))
         if hasattr(value, 'contribute_to_class'):
             value.contribute_to_class(cls, name)
         else: