diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index d57417d92..91af2af2d 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -424,9 +424,8 @@ class ModelSerializer(Serializer):
         """
 
         cls = self.opts.model
-        if cls is None:
-            raise AttributeError("Serializer class '%s' is missing 'model' Meta option" %
-                                 self.__class__.__name__)
+        assert cls is not None, \
+                "Serializer class '%s' is missing 'model' Meta option" % self.__class__.__name__
         opts = get_concrete_model(cls)._meta
         pk_field = opts.pk
         # while pk_field.rel:
diff --git a/rest_framework/tests/serializer.py b/rest_framework/tests/serializer.py
index d4e9cc132..36703fd9c 100644
--- a/rest_framework/tests/serializer.py
+++ b/rest_framework/tests/serializer.py
@@ -365,7 +365,7 @@ class ValidationTests(TestCase):
         """
         try:
             serializer = BrokenModelSerializer()
-        except AttributeError as e:
+        except AssertionError as e:
             self.assertEquals(e.args[0], "Serializer class 'BrokenModelSerializer' is missing 'model' Meta option")
         except:
             self.fail('Wrong exception type thrown.')