diff --git a/lower-constraints.txt b/lower-constraints.txt
index 8675c23..4b0da0e 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -14,7 +14,6 @@ iso8601==0.1.11
 keystoneauth1==3.4.0
 linecache2==1.0.0
 mccabe==0.2.1
-mock==2.0.0
 mox3==0.20.0
 msgpack==0.5.2
 netaddr==0.7.18
diff --git a/oslo_serialization/tests/test_jsonutils.py b/oslo_serialization/tests/test_jsonutils.py
index 2a8de67..e04b9dc 100644
--- a/oslo_serialization/tests/test_jsonutils.py
+++ b/oslo_serialization/tests/test_jsonutils.py
@@ -20,9 +20,9 @@ import io
 import ipaddress
 import itertools
 import json
+from unittest import mock
 from xmlrpc import client as xmlrpclib
 
-import mock
 import netaddr
 from oslo_i18n import fixture
 from oslotest import base as test_base
diff --git a/test-requirements.txt b/test-requirements.txt
index 232fb68..628bfee 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -2,7 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 hacking>=1.1.0,<1.2.0 # Apache-2.0
-mock>=2.0.0 # BSD
 netaddr>=0.7.18 # BSD
 stestr>=2.0.0 # Apache-2.0