diff --git a/ironic/tests/unit/api/controllers/test_base.py b/ironic/tests/unit/api/controllers/test_base.py
index 423eaffa52..b94f66f65c 100644
--- a/ironic/tests/unit/api/controllers/test_base.py
+++ b/ironic/tests/unit/api/controllers/test_base.py
@@ -14,8 +14,8 @@
 #    under the License.
 
 from http import client as http_client
+from unittest import mock
 
-import mock
 from webob import exc
 
 from ironic.api.controllers import base as cbase
diff --git a/ironic/tests/unit/api/controllers/v1/test_allocation.py b/ironic/tests/unit/api/controllers/v1/test_allocation.py
index 7f5cbd2ce9..7409ea2ae9 100644
--- a/ironic/tests/unit/api/controllers/v1/test_allocation.py
+++ b/ironic/tests/unit/api/controllers/v1/test_allocation.py
@@ -15,10 +15,10 @@ Tests for the API /allocations/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 from urllib import parse as urlparse
 
 import fixtures
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_chassis.py b/ironic/tests/unit/api/controllers/v1/test_chassis.py
index 13768b7b3a..69b83e4ac9 100644
--- a/ironic/tests/unit/api/controllers/v1/test_chassis.py
+++ b/ironic/tests/unit/api/controllers/v1/test_chassis.py
@@ -17,9 +17,9 @@ Tests for the API /chassis/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 from urllib import parse as urlparse
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_conductor.py b/ironic/tests/unit/api/controllers/v1/test_conductor.py
index c639346d49..caf85eb4c2 100644
--- a/ironic/tests/unit/api/controllers/v1/test_conductor.py
+++ b/ironic/tests/unit/api/controllers/v1/test_conductor.py
@@ -15,8 +15,8 @@ Tests for the API /conductors/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_deploy_template.py b/ironic/tests/unit/api/controllers/v1/test_deploy_template.py
index 5f49e65d12..6f5b6e64cb 100644
--- a/ironic/tests/unit/api/controllers/v1/test_deploy_template.py
+++ b/ironic/tests/unit/api/controllers/v1/test_deploy_template.py
@@ -15,9 +15,9 @@ Tests for the API /deploy_templates/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 from urllib import parse as urlparse
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_driver.py b/ironic/tests/unit/api/controllers/v1/test_driver.py
index bd4bb92cc9..18100874d2 100644
--- a/ironic/tests/unit/api/controllers/v1/test_driver.py
+++ b/ironic/tests/unit/api/controllers/v1/test_driver.py
@@ -15,8 +15,8 @@
 
 from http import client as http_client
 import json
+from unittest import mock
 
-import mock
 from oslo_config import cfg
 from testtools import matchers
 
diff --git a/ironic/tests/unit/api/controllers/v1/test_event.py b/ironic/tests/unit/api/controllers/v1/test_event.py
index 082c74493e..b67870c232 100644
--- a/ironic/tests/unit/api/controllers/v1/test_event.py
+++ b/ironic/tests/unit/api/controllers/v1/test_event.py
@@ -14,8 +14,7 @@ Tests for the API /events methods.
 """
 
 from http import client as http_client
-
-import mock
+from unittest import mock
 
 from ironic.api.controllers import base as api_base
 from ironic.api.controllers.v1 import types
diff --git a/ironic/tests/unit/api/controllers/v1/test_expose.py b/ironic/tests/unit/api/controllers/v1/test_expose.py
index 0cb41b22dd..9cb8e96ab8 100644
--- a/ironic/tests/unit/api/controllers/v1/test_expose.py
+++ b/ironic/tests/unit/api/controllers/v1/test_expose.py
@@ -19,8 +19,8 @@ import inspect
 import json
 import os
 import sys
+from unittest import mock
 
-import mock
 from oslo_utils import uuidutils
 import pecan.rest
 import pecan.testing
diff --git a/ironic/tests/unit/api/controllers/v1/test_node.py b/ironic/tests/unit/api/controllers/v1/test_node.py
index b042efaa98..bd036f6199 100644
--- a/ironic/tests/unit/api/controllers/v1/test_node.py
+++ b/ironic/tests/unit/api/controllers/v1/test_node.py
@@ -17,10 +17,10 @@ import datetime
 from http import client as http_client
 import json
 import os
+from unittest import mock
 from urllib import parse as urlparse
 
 import fixtures
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_notification_utils.py b/ironic/tests/unit/api/controllers/v1/test_notification_utils.py
index 30c8df134b..d7e3e7e828 100644
--- a/ironic/tests/unit/api/controllers/v1/test_notification_utils.py
+++ b/ironic/tests/unit/api/controllers/v1/test_notification_utils.py
@@ -12,7 +12,8 @@
 
 """Test class for ironic-api notification utilities."""
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from ironic.api.controllers.v1 import notification_utils as notif_utils
diff --git a/ironic/tests/unit/api/controllers/v1/test_port.py b/ironic/tests/unit/api/controllers/v1/test_port.py
index 4c2744b70d..24df8bf265 100644
--- a/ironic/tests/unit/api/controllers/v1/test_port.py
+++ b/ironic/tests/unit/api/controllers/v1/test_port.py
@@ -16,9 +16,9 @@ Tests for the API /ports/ methods.
 import datetime
 from http import client as http_client
 import types
+from unittest import mock
 from urllib import parse as urlparse
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_portgroup.py b/ironic/tests/unit/api/controllers/v1/test_portgroup.py
index 0c90cd7b21..8d66c414df 100644
--- a/ironic/tests/unit/api/controllers/v1/test_portgroup.py
+++ b/ironic/tests/unit/api/controllers/v1/test_portgroup.py
@@ -15,9 +15,9 @@ Tests for the API /portgroups/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 from urllib import parse as urlparse
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_ramdisk.py b/ironic/tests/unit/api/controllers/v1/test_ramdisk.py
index 2321466978..1b233fc701 100644
--- a/ironic/tests/unit/api/controllers/v1/test_ramdisk.py
+++ b/ironic/tests/unit/api/controllers/v1/test_ramdisk.py
@@ -16,9 +16,9 @@ Tests for the API /lookup/ methods.
 """
 
 from http import client as http_client
+from unittest import mock
 
 import fixtures
-import mock
 from oslo_config import cfg
 from oslo_utils import uuidutils
 
diff --git a/ironic/tests/unit/api/controllers/v1/test_root.py b/ironic/tests/unit/api/controllers/v1/test_root.py
index 449c65defd..3d8408f1c2 100644
--- a/ironic/tests/unit/api/controllers/v1/test_root.py
+++ b/ironic/tests/unit/api/controllers/v1/test_root.py
@@ -12,7 +12,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
+
 from webob import exc as webob_exc
 
 from ironic.api.controllers import v1 as v1_api
diff --git a/ironic/tests/unit/api/controllers/v1/test_types.py b/ironic/tests/unit/api/controllers/v1/test_types.py
index d8c369b30a..40f8ea0c4e 100644
--- a/ironic/tests/unit/api/controllers/v1/test_types.py
+++ b/ironic/tests/unit/api/controllers/v1/test_types.py
@@ -17,8 +17,8 @@
 
 from http import client as http_client
 import platform
+from unittest import mock
 
-import mock
 from pecan import rest
 
 from ironic.api.controllers.v1 import types
diff --git a/ironic/tests/unit/api/controllers/v1/test_utils.py b/ironic/tests/unit/api/controllers/v1/test_utils.py
index e33617d747..d4c8882220 100644
--- a/ironic/tests/unit/api/controllers/v1/test_utils.py
+++ b/ironic/tests/unit/api/controllers/v1/test_utils.py
@@ -15,8 +15,8 @@
 #    under the License.
 
 from http import client as http_client
+from unittest import mock
 
-import mock
 import os_traits
 from oslo_config import cfg
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_versions.py b/ironic/tests/unit/api/controllers/v1/test_versions.py
index 3025429506..f6fc528fcd 100644
--- a/ironic/tests/unit/api/controllers/v1/test_versions.py
+++ b/ironic/tests/unit/api/controllers/v1/test_versions.py
@@ -16,8 +16,7 @@ Tests for the versions constants and methods.
 """
 
 import re
-
-import mock
+from unittest import mock
 
 from ironic.api.controllers.v1 import versions
 from ironic.common import release_mappings
diff --git a/ironic/tests/unit/api/controllers/v1/test_volume_connector.py b/ironic/tests/unit/api/controllers/v1/test_volume_connector.py
index 741ba78203..2c5f239447 100644
--- a/ironic/tests/unit/api/controllers/v1/test_volume_connector.py
+++ b/ironic/tests/unit/api/controllers/v1/test_volume_connector.py
@@ -17,9 +17,9 @@ Tests for the API /volume connectors/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 from urllib import parse as urlparse
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/ironic/tests/unit/api/controllers/v1/test_volume_target.py b/ironic/tests/unit/api/controllers/v1/test_volume_target.py
index 1587461e7c..613f551a48 100644
--- a/ironic/tests/unit/api/controllers/v1/test_volume_target.py
+++ b/ironic/tests/unit/api/controllers/v1/test_volume_target.py
@@ -17,9 +17,9 @@ Tests for the API /volume targets/ methods.
 
 import datetime
 from http import client as http_client
+from unittest import mock
 from urllib import parse as urlparse
 
-import mock
 from oslo_config import cfg
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
diff --git a/lower-constraints.txt b/lower-constraints.txt
index 24866cb842..c57bd2bcf0 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -50,7 +50,6 @@ logutils==0.3.5
 Mako==1.1.2
 MarkupSafe==1.1.1
 mccabe==0.6.1
-mock==4.0.2
 monotonic==1.5
 mox3==1.0.0
 msgpack-python==0.5.6