diff --git a/cachalot/tests/models.py b/cachalot/tests/models.py
index e6e9802..5eab11f 100644
--- a/cachalot/tests/models.py
+++ b/cachalot/tests/models.py
@@ -4,7 +4,7 @@ from __future__ import unicode_literals
 
 from django.conf import settings
 from django.db.models import (
-    Model, CharField, ForeignKey, BooleanField, DateField, DateTimeField, ManyToManyField)
+    Model, CharField, ForeignKey, BooleanField, DateField, DateTimeField)
 
 
 class Test(Model):
@@ -32,12 +32,3 @@ class TestChild(TestParent):
 
     class Meta(object):
         app_label = 'cachalot'
-
-
-class TestOne(Model):
-    name = CharField(max_length=20)
-    have_lots_of_these = ManyToManyField('TestThese', blank=True, null=True)
-
-
-class TestThese(Model):
-    name = CharField(max_length=20)
diff --git a/cachalot/tests/write.py b/cachalot/tests/write.py
index 9e501be..9279769 100644
--- a/cachalot/tests/write.py
+++ b/cachalot/tests/write.py
@@ -14,7 +14,7 @@ from django.db import connection, transaction
 from django.db.models import Count
 from django.test import TransactionTestCase, skipUnlessDBFeature
 
-from .models import Test, TestParent, TestChild, TestOne, TestThese
+from .models import Test, TestParent, TestChild
 
 
 class WriteTestCase(TransactionTestCase):
@@ -373,6 +373,16 @@ class WriteTestCase(TransactionTestCase):
             )
         self.assertListEqual(data10, [])
 
+        with self.assertNumQueries(1):
+            data11 = list(User.objects.exclude(user_permissions=None))
+        self.assertListEqual(data11, [u])
+
+        u.user_permissions.clear()
+
+        with self.assertNumQueries(1):
+            data12 = list(User.objects.exclude(user_permissions=None))
+        self.assertListEqual(data12, [])
+
     def test_invalidate_nested_subqueries(self):
         with self.assertNumQueries(1):
             data1 = list(
@@ -810,88 +820,6 @@ class WriteTestCase(TransactionTestCase):
                 list(Test.objects.values_list('name', flat=True)),
                 [])
 
-    def test_clear_with_filters(self):
-        names = ['Thing 1', 'Thing 2', 'Thing 3']
-        for name in names:
-            thing = TestThese()
-            thing.name = name
-            thing.save()
-        hub = TestOne()
-        hub.name = 'Has lots'
-        hub.save()
-        for thing in TestThese.objects.all():
-            hub.have_lots_of_these.add(thing)
-        hub.save()
-        # read the number of things that hub has got
-        with self.assertNumQueries(1):
-            nt = list(hub.have_lots_of_these.all())
-        self.assertEqual(3, len(nt))
-
-        # read it again
-        with self.assertNumQueries(0):
-            list(hub.have_lots_of_these.all())
-
-        # read the number of TestOnes that have no things
-        with self.assertNumQueries(1):
-            ns = TestOne.objects.filter(have_lots_of_these=None).count()
-        self.assertEqual(ns, 0)
-
-        # now do a .clear on hub (which is a TestOne) and make sure db is queried for subsequent read
-        hub.have_lots_of_these.clear()
-        with self.assertNumQueries(1):
-            things = list(hub.have_lots_of_these.all())
-        self.assertEqual(0, len(things))
-
-        # again, query for the number of TestOnes that have no things. There
-        # should be one now
-        with self.assertNumQueries(1):
-            ns = TestOne.objects.filter(have_lots_of_these=None).count()
-            # there should now be one
-        self.assertEqual(ns, 1)
-
-    def test_clear_with_excludes(self):
-        '''
-        same test as above but using excludes rather than filters
-        '''
-        names = ['Thing 1', 'Thing 2', 'Thing 3']
-        for name in names:
-            thing = TestThese()
-            thing.name = name
-            thing.save()
-        hub = TestOne()
-        hub.name = 'Has lots'
-        hub.save()
-        for thing in TestThese.objects.all():
-            hub.have_lots_of_these.add(thing)
-        hub.save()
-
-        # read the number of things that hub has got
-        with self.assertNumQueries(1):
-            nt = list(hub.have_lots_of_these.all())
-        self.assertEqual(3, len(nt))
-
-        # read it again
-        with self.assertNumQueries(0):
-            list(hub.have_lots_of_these.all())
-
-        # read the number of TestOnes that have things via an exclude
-        # there should be one
-        with self.assertNumQueries(1):
-            ns = TestOne.objects.exclude(have_lots_of_these=None).count()
-        self.assertEqual(ns, 1)
-
-        # now do a .clear on hub (which is a TestOne) and make sure db is queried for subsequent read
-        hub.have_lots_of_these.clear()
-        with self.assertNumQueries(1):
-            things = list(hub.have_lots_of_these.all())
-        self.assertEqual(0, len(things))
-
-        # again, query for the number of TestOnes that have things. There
-        # should be none now
-        with self.assertNumQueries(1):
-            ns = TestOne.objects.exclude(have_lots_of_these=None).count()
-        self.assertEqual(ns, 0)
-
 
 class DatabaseCommandTestCase(TransactionTestCase):
     def setUp(self):