diff --git a/lower-constraints.txt b/lower-constraints.txt
index 27ecde6..986794b 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -24,7 +24,6 @@ keystoneauth1==3.4.0
 linecache2==1.0.0
 MarkupSafe==1.0
 mccabe==0.2.1
-mock==2.0.0
 monotonic==0.6
 mox3==0.20.0
 netaddr==0.7.18
diff --git a/oslo_concurrency/tests/unit/test_lockutils.py b/oslo_concurrency/tests/unit/test_lockutils.py
index 1bd74a2..3ebdd71 100644
--- a/oslo_concurrency/tests/unit/test_lockutils.py
+++ b/oslo_concurrency/tests/unit/test_lockutils.py
@@ -21,8 +21,8 @@ import sys
 import tempfile
 import threading
 import time
+from unittest import mock
 
-import mock
 from oslo_config import cfg
 from oslotest import base as test_base
 import six
diff --git a/oslo_concurrency/tests/unit/test_processutils.py b/oslo_concurrency/tests/unit/test_processutils.py
index 982d293..2205bfa 100644
--- a/oslo_concurrency/tests/unit/test_processutils.py
+++ b/oslo_concurrency/tests/unit/test_processutils.py
@@ -26,9 +26,9 @@ import stat
 import subprocess
 import sys
 import tempfile
+from unittest import mock
 
 import fixtures
-import mock
 from oslotest import base as test_base
 import six