diff --git a/nova/test.py b/nova/test.py
index 45e7015715d1..904abd72fe76 100644
--- a/nova/test.py
+++ b/nova/test.py
@@ -30,7 +30,6 @@ import inspect
 import logging
 import os
 import shutil
-import sys
 import uuid
 
 import fixtures
@@ -150,23 +149,6 @@ class SampleNetworks(fixtures.Fixture):
             network.set_network_host(ctxt, net)
 
 
-class ReplaceModule(fixtures.Fixture):
-    """Replace a module with a fake module."""
-
-    def __init__(self, name, new_value):
-        self.name = name
-        self.new_value = new_value
-
-    def _restore(self, old_value):
-        sys.modules[self.name] = old_value
-
-    def setUp(self):
-        super(ReplaceModule, self).setUp()
-        old_value = sys.modules.get(self.name)
-        sys.modules[self.name] = self.new_value
-        self.addCleanup(self._restore, old_value)
-
-
 class ServiceFixture(fixtures.Fixture):
     """Run a service as a test fixture."""
 
diff --git a/nova/tests/unit/network/test_manager.py b/nova/tests/unit/network/test_manager.py
index 393e59ca5b8b..2de6e345f521 100644
--- a/nova/tests/unit/network/test_manager.py
+++ b/nova/tests/unit/network/test_manager.py
@@ -3371,7 +3371,9 @@ class LdapDNSTestCase(test.TestCase):
     def setUp(self):
         super(LdapDNSTestCase, self).setUp()
 
-        self.useFixture(test.ReplaceModule('ldap', fake_ldap))
+        self.useFixture(fixtures.MonkeyPatch(
+            'nova.network.ldapdns.ldap',
+            fake_ldap))
         dns_class = 'nova.network.ldapdns.LdapDNS'
         self.driver = importutils.import_object(dns_class)
 
diff --git a/nova/tests/unit/virt/xenapi/stubs.py b/nova/tests/unit/virt/xenapi/stubs.py
index ad13ca41df85..a6395b6004be 100644
--- a/nova/tests/unit/virt/xenapi/stubs.py
+++ b/nova/tests/unit/virt/xenapi/stubs.py
@@ -15,7 +15,9 @@
 
 import pickle
 import random
+import sys
 
+import fixtures
 from oslo.serialization import jsonutils
 
 from nova import test
@@ -263,6 +265,23 @@ def stub_out_vm_methods(stubs):
     stubs.Set(vm_utils, '_wait_for_device', fake_wait_for_device)
 
 
+class ReplaceModule(fixtures.Fixture):
+    """Replace a module with a fake module."""
+
+    def __init__(self, name, new_value):
+        self.name = name
+        self.new_value = new_value
+
+    def _restore(self, old_value):
+        sys.modules[self.name] = old_value
+
+    def setUp(self):
+        super(ReplaceModule, self).setUp()
+        old_value = sys.modules.get(self.name)
+        sys.modules[self.name] = self.new_value
+        self.addCleanup(self._restore, old_value)
+
+
 class FakeSessionForVolumeTests(fake.SessionBase):
     """Stubs out a XenAPISession for Volume tests."""
     def VDI_introduce(self, _1, uuid, _2, _3, _4, _5,
@@ -354,12 +373,12 @@ class FakeSessionForFailedMigrateTests(FakeSessionForVMTests):
 class XenAPITestBase(test.TestCase):
     def setUp(self):
         super(XenAPITestBase, self).setUp()
-        self.useFixture(test.ReplaceModule('XenAPI', fake))
+        self.useFixture(ReplaceModule('XenAPI', fake))
         fake.reset()
 
 
 class XenAPITestBaseNoDB(test.NoDBTestCase):
     def setUp(self):
         super(XenAPITestBaseNoDB, self).setUp()
-        self.useFixture(test.ReplaceModule('XenAPI', fake))
+        self.useFixture(ReplaceModule('XenAPI', fake))
         fake.reset()