diff --git a/polymorphic/__init__.py b/polymorphic/__init__.py
index 7f4f0fd..83ced79 100644
--- a/polymorphic/__init__.py
+++ b/polymorphic/__init__.py
@@ -25,33 +25,37 @@ def get_version():
         version += ' %s' % VERSION[3]
     return version
 
-
-# Proxied models need to have it's own ContentType
-
-
 from django.contrib.contenttypes.models import ContentTypeManager
 from django.utils.encoding import smart_unicode
 
 
-def get_for_proxied_model(self, model):
-    """
-    Returns the ContentType object for a given model, creating the
-    ContentType if necessary. Lookups are cached so that subsequent lookups
-    for the same model don't hit the database.
-    """
+# Monkey-patch Django to allow ContentTypes for proxy models. This is compatible with an
+# upcoming change in Django 1.5 and should be removed when we upgrade. There is a test
+# in MonkeyPatchTests that checks for this.
+# https://code.djangoproject.com/ticket/18399
+
+def get_for_model(self, model, for_concrete_model=True):
+    from django.utils.encoding import smart_unicode
+
+    if for_concrete_model:
+        model = model._meta.concrete_model
+    elif model._deferred:
+        model = model._meta.proxy_for_model
+
     opts = model._meta
-    key = (opts.app_label, opts.object_name.lower())
+
     try:
-        ct = self.__class__._cache[self.db][key]
+        ct = self._get_from_cache(opts)
     except KeyError:
-        # Load or create the ContentType entry. The smart_unicode() is
-        # needed around opts.verbose_name_raw because name_raw might be a
-        # django.utils.functional.__proxy__ object.
         ct, created = self.get_or_create(
-            app_label=opts.app_label,
-            model=opts.object_name.lower(),
-            defaults={'name': smart_unicode(opts.verbose_name_raw)},
+            app_label = opts.app_label,
+            model = opts.object_name.lower(),
+            defaults = {'name': smart_unicode(opts.verbose_name_raw)},
         )
         self._add_to_cache(self.db, ct)
+
     return ct
-ContentTypeManager.get_for_proxied_model = get_for_proxied_model
+
+ContentTypeManager.get_for_model__original = ContentTypeManager.get_for_model
+ContentTypeManager.get_for_model = get_for_model
+
diff --git a/polymorphic/polymorphic_model.py b/polymorphic/polymorphic_model.py
index baf986c..cca724d 100644
--- a/polymorphic/polymorphic_model.py
+++ b/polymorphic/polymorphic_model.py
@@ -85,7 +85,7 @@ class PolymorphicModel(models.Model):
         (used by PolymorphicQuerySet._get_real_instances)
         """
         if not self.polymorphic_ctype_id:
-            self.polymorphic_ctype = ContentType.objects.get_for_model(self)
+            self.polymorphic_ctype = ContentType.objects.get_for_model(self, for_concrete_model=False)
 
     def save(self, *args, **kwargs):
         """Overridden model save function which supports the polymorphism
diff --git a/polymorphic/query.py b/polymorphic/query.py
index ac097a5..860e8fd 100644
--- a/polymorphic/query.py
+++ b/polymorphic/query.py
@@ -135,7 +135,7 @@ class PolymorphicQuerySet(QuerySet):
         # - also record the correct result order in "ordered_id_list"
         # - store objects that already have the correct class into "results"
         base_result_objects_by_id = {}
-        self_model_content_type_id = ContentType.objects.get_for_model(self.model).pk
+        self_model_content_type_id = ContentType.objects.get_for_model(self.model, for_concrete_model=False).pk
         for base_object in base_result_objects:
             ordered_id_list.append(base_object.pk)
 
diff --git a/polymorphic/query_translate.py b/polymorphic/query_translate.py
index 2d1b730..e42e349 100644
--- a/polymorphic/query_translate.py
+++ b/polymorphic/query_translate.py
@@ -220,7 +220,7 @@ def _create_model_filter_Q(modellist, not_instance_of=False):
             assert False, 'PolymorphicModel: instance_of expects a list of (polymorphic) models or a single (polymorphic) model'
 
     def q_class_with_subclasses(model):
-        q = Q(polymorphic_ctype=ContentType.objects.get_for_model(model))
+        q = Q(polymorphic_ctype=ContentType.objects.get_for_model(model, for_concrete_model=False))
         for subclass in model.__subclasses__():
             q = q | q_class_with_subclasses(subclass)
         return q
diff --git a/polymorphic/tests.py b/polymorphic/tests.py
index ecf4c52..dac0825 100644
--- a/polymorphic/tests.py
+++ b/polymorphic/tests.py
@@ -749,3 +749,37 @@ class RegressionTests(TestCase):
         expected_queryset = [bottom]
         self.assertQuerysetEqual(Bottom.objects.all(), [repr(r) for r in expected_queryset])
 
+
+class MonkeyPatchTests(TestCase):
+
+    def test_content_types_for_proxy_models_patch(self):
+        from django.db.models import Model
+        from django.contrib.contenttypes.models import ContentType
+
+        class Base(Model):
+            pass
+
+        class Proxy(Base):
+            class Meta:
+                proxy = True
+
+        ct = ContentType.objects.get_for_model(Proxy, for_concrete_model=False)
+        self.assertEqual(Proxy, ct.model_class())
+
+    def test_content_types_for_proxy_models_patch_still_required(self):
+        """
+        If this test fails then our monkey patch of ContentTypeManager.get_for_model
+        is no longer required and should be removed
+        """
+        from django.db.models import Model
+        from django.contrib.contenttypes.models import ContentType
+
+        class MyModel(Model):
+            pass
+
+        self.assertRaisesMessage(
+            TypeError,
+            "get_for_model() got an unexpected keyword argument 'for_concrete_model'",
+            ContentType.objects.get_for_model__original,
+            MyModel, for_concrete_model=False
+        )