diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index c0449e7047..b8638fe909 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -921,8 +921,7 @@ class Query(object):
         """
         opts = model._meta
         field_list = aggregate.lookup.split(LOOKUP_SEP)
-        if (len(field_list) == 1 and
-            aggregate.lookup in self.aggregates.keys()):
+        if len(field_list) == 1 and aggregate.lookup in self.aggregates:
             # Aggregate is over an annotation
             field_name = field_list[0]
             col = field_name
@@ -1090,11 +1089,14 @@ class Query(object):
                         if self.alias_map[alias][JOIN_TYPE] == self.LOUTER:
                             j_col = self.alias_map[alias][RHS_JOIN_COL]
                             entry = self.where_class()
-                            entry.add((Constraint(alias, j_col, None), 'isnull', True), AND)
+                            entry.add(
+                                (Constraint(alias, j_col, None), 'isnull', True),
+                                AND
+                            )
                             entry.negate()
                             self.where.add(entry, AND)
                             break
-                elif not (lookup_type == 'in'
+                if not (lookup_type == 'in'
                             and not hasattr(value, 'as_sql')
                             and not hasattr(value, '_as_sql')
                             and not value) and field.null:
diff --git a/tests/regressiontests/model_inheritance_regress/tests.py b/tests/regressiontests/model_inheritance_regress/tests.py
index 569cef5845..dac2cb5de5 100644
--- a/tests/regressiontests/model_inheritance_regress/tests.py
+++ b/tests/regressiontests/model_inheritance_regress/tests.py
@@ -3,12 +3,16 @@ Regression tests for Model inheritance behaviour.
 """
 
 import datetime
+from operator import attrgetter
+
 from django.test import TestCase
-from regressiontests.model_inheritance_regress.models import (
-    Place, Restaurant, ItalianRestaurant, ParkingLot, ParkingLot2,
-    ParkingLot3, Supplier, Wholesaler, Child, SelfRefChild, ArticleWithAuthor,
-    M2MChild, QualityControl, DerivedM, Person, BirthdayParty, BachelorParty,
-    MessyBachelorParty, InternalCertificationAudit)
+
+from models import (Place, Restaurant, ItalianRestaurant, ParkingLot,
+    ParkingLot2, ParkingLot3, Supplier, Wholesaler, Child, SelfRefParent,
+    SelfRefChild, ArticleWithAuthor, M2MChild, QualityControl, DerivedM,
+    Person, BirthdayParty, BachelorParty, MessyBachelorParty,
+    InternalCertificationAudit)
+
 
 class ModelInheritanceTest(TestCase):
     def test_model_inheritance(self):
@@ -355,7 +359,10 @@ class ModelInheritanceTest(TestCase):
         self.assertEqual(parties, [bachelor, messy_parent])
 
     def test_11369(self):
-        """verbose_name_plural correctly inherited from ABC if inheritance chain includes an abstract model."""
+        """
+        verbose_name_plural correctly inherited from ABC if inheritance chain
+        includes an abstract model.
+        """
         # Regression test for #11369: verbose_name_plural should be inherited
         # from an ABC even when there are one or more intermediate
         # abstract models in the inheritance chain, for consistency with
@@ -364,3 +371,18 @@ class ModelInheritanceTest(TestCase):
                 InternalCertificationAudit._meta.verbose_name_plural,
                 u'Audits'
         )
+
+    def test_inherited_nullable_exclude(self):
+        obj = SelfRefChild.objects.create(child_data=37, parent_data=42)
+        self.assertQuerysetEqual(
+            SelfRefParent.objects.exclude(self_data=72), [
+                obj.pk
+            ],
+            attrgetter("pk")
+        )
+        self.assertQuerysetEqual(
+            SelfRefChild.objects.exclude(self_data=72), [
+                obj.pk
+            ],
+            attrgetter("pk")
+        )