diff --git a/octaviaclient/tests/fakes.py b/octaviaclient/tests/fakes.py
index 61a9412..5676e76 100644
--- a/octaviaclient/tests/fakes.py
+++ b/octaviaclient/tests/fakes.py
@@ -14,10 +14,11 @@
 #
 
 import copy
-import json
 import mock
 import sys
 
+from oslo_serialization import jsonutils
+
 from keystoneauth1 import fixture
 import requests
 import six
@@ -242,7 +243,7 @@ class FakeResponse(requests.Response):
         self.status_code = status_code
 
         self.headers.update(headers)
-        self._content = json.dumps(data)
+        self._content = jsonutils.dumps(data)
         if not isinstance(self._content, six.binary_type):
             self._content = self._content.encode()