diff --git a/polymorphic/managers.py b/polymorphic/managers.py
index 06f52c8..f20cd83 100644
--- a/polymorphic/managers.py
+++ b/polymorphic/managers.py
@@ -38,18 +38,18 @@ class PolymorphicManager(models.Manager):
     if django.VERSION < (1, 7):
         get_query_set = get_queryset
 
-    # Proxy all unknown method calls to the queryset, so that its members are
-    # directly accessible as PolymorphicModel.objects.*
-    # The advantage of this method is that not yet known member functions of derived querysets will be proxied as well.
-    # We exclude any special functions (__) from this automatic proxying.
-    #
-    # NOTE: Fetching the queryset is done by calling self.all() here on purpose.
-    # By using .all(), the proper get_query_set()/get_queryset() will be used for each Django version.
-    # Django 1.4/1.5 need to use get_query_set(), because the RelatedManager overrides that.
-    def __getattr__(self, name):
-        if name.startswith('__'):
-            return super(PolymorphicManager, self).__getattr__(self, name)
-        return getattr(self.all(), name)
-
     def __unicode__(self):
         return '%s (PolymorphicManager) using %s' % (self.__class__.__name__, self.queryset_class.__name__)
+
+    # Proxied methods
+    def non_polymorphic(self):
+        return self.all().non_polymorphic()
+
+    def instance_of(self, *args):
+        return self.all().instance_of(*args)
+
+    def not_instance_of(self, *args):
+        return self.all().not_instance_of(*args)
+
+    def get_real_instances(self, base_result_objects=None):
+        return self.all().get_real_instances(base_result_objects=base_result_objects)
diff --git a/polymorphic/query.py b/polymorphic/query.py
index 068ef47..61071dc 100644
--- a/polymorphic/query.py
+++ b/polymorphic/query.py
@@ -82,7 +82,7 @@ class PolymorphicQuerySet(QuerySet):
         as_manager.queryset_only = True
         as_manager = classmethod(as_manager)
 
-    def non_polymorphic(self, *args, **kwargs):
+    def non_polymorphic(self):
         """switch off polymorphic behaviour for this query.
         When the queryset is evaluated, only objects of the type of the
         base class used for this query are returned."""
diff --git a/polymorphic/tests.py b/polymorphic/tests.py
index f11f9cd..b67f584 100644
--- a/polymorphic/tests.py
+++ b/polymorphic/tests.py
@@ -174,6 +174,9 @@ class MyManager(PolymorphicManager):
     def get_queryset(self):
         return super(MyManager, self).get_queryset().order_by('-field1')
 
+    def my_queryset_foo(self):
+        return self.all().my_queryset_foo()
+
     # Django <= 1.5 compatibility
     get_query_set = get_queryset