diff --git a/heat/tests/openstack/ironic/test_port.py b/heat/tests/openstack/ironic/test_port.py
index ac603ea955..4e9326f544 100644
--- a/heat/tests/openstack/ironic/test_port.py
+++ b/heat/tests/openstack/ironic/test_port.py
@@ -12,8 +12,9 @@
 #    under the License.
 
 import copy
+from unittest import mock
+
 from ironicclient.common.apiclient import exceptions as ic_exc
-import mock
 from oslo_config import cfg
 
 from heat.common import exception
diff --git a/lower-constraints.txt b/lower-constraints.txt
index 35874684d6..d2699c73e1 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -48,7 +48,6 @@ lxml==3.4.1
 Mako==1.0.7
 MarkupSafe==1.0
 mccabe==0.2.1
-mock==2.0.0
 monotonic==1.4
 msgpack==0.5.6
 munch==2.2.0