diff --git a/src/pdm/framework/RESTClient.py b/src/pdm/framework/RESTClient.py
index 32664bba..cfecba1c 100644
--- a/src/pdm/framework/RESTClient.py
+++ b/src/pdm/framework/RESTClient.py
@@ -170,10 +170,10 @@ def patch_client(target, test_client, base_uri='/'):
         # We import mock here as TestClient is only meant for use in the tests
         # If we import it globally, it'll break importing this module in
         # production.
-        import mock
+        import unittest.mock
         # We patch away the base class of the target, replacing it with
         # RESTClientTest instead.
-        patcher = mock.patch.object(target, '__bases__', (RESTClientTest, ))
+        patcher = unittest.mock.patch.object(target, '__bases__', (RESTClientTest, ))
         patcher.start()
         # is_local is required to prevent mock from attempting to delete
         # __bases__ when stop is called (which would throw an exception)
diff --git a/test/pdm/CLI/test_usercommand.py b/test/pdm/CLI/test_usercommand.py
index a6cfbfcc..394b1984 100644
--- a/test/pdm/CLI/test_usercommand.py
+++ b/test/pdm/CLI/test_usercommand.py
@@ -1,5 +1,5 @@
-import mock
 import unittest
+import unittest.mock as mock
 import argparse
 import tempfile
 import datetime
diff --git a/test/pdm/demo/test_DemoClient.py b/test/pdm/demo/test_DemoClient.py
index 0245b4ab..323d87f4 100644
--- a/test/pdm/demo/test_DemoClient.py
+++ b/test/pdm/demo/test_DemoClient.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 
-import mock
 import unittest
+import unittest.mock as mock
 
 from pdm.demo.DemoClient import DemoClient
 from pdm.demo.DemoService import DemoService
diff --git a/test/pdm/framework/test_Database.py b/test/pdm/framework/test_Database.py
index 5070121b..c5c05407 100644
--- a/test/pdm/framework/test_Database.py
+++ b/test/pdm/framework/test_Database.py
@@ -1,10 +1,10 @@
 #!/usr/bin/env
 """ Framework database object tests. """
 
-import mock
 import json
 import datetime
 import unittest
+import unittest.mock as mock
 
 from pdm.framework.Database import MemSafeSQLAlchemy
 from pdm.framework.Database import JSONMixin, JSONTableEncoder
diff --git a/test/pdm/framework/test_RESTClient.py b/test/pdm/framework/test_RESTClient.py
index 7b06165b..d1921f3c 100644
--- a/test/pdm/framework/test_RESTClient.py
+++ b/test/pdm/framework/test_RESTClient.py
@@ -2,8 +2,8 @@
 """ Test RESTClient framework module. """
 
 import json
-import mock
 import unittest
+import unittest.mock as mock
 import functools
 import requests
 
diff --git a/test/pdm/framework/test_WSGIServer.py b/test/pdm/framework/test_WSGIServer.py
index 2d0c5458..12a8ae17 100644
--- a/test/pdm/framework/test_WSGIServer.py
+++ b/test/pdm/framework/test_WSGIServer.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 """ Tests for the WSGIServer module. """
 
-import mock
 import unittest
+import unittest.mock as mock
 
 from pdm.framework.WSGIServer import WSGIAuth, WSGIServer
 
diff --git a/test/pdm/site/test_SiteClient.py b/test/pdm/site/test_SiteClient.py
index 85caaa95..5e81b44c 100644
--- a/test/pdm/site/test_SiteClient.py
+++ b/test/pdm/site/test_SiteClient.py
@@ -1,10 +1,10 @@
 #!/usr/bin/env python
 """ Test SiteService client class. """
 
-import mock
 import logging
 import datetime
 import unittest
+import unittest.mock as mock
 
 from pdm.site.SiteClient import SiteClient
 from pdm.site.SiteService import SiteService
diff --git a/test/pdm/site/test_SiteService.py b/test/pdm/site/test_SiteService.py
index 158dc34d..b71e3ab4 100644
--- a/test/pdm/site/test_SiteService.py
+++ b/test/pdm/site/test_SiteService.py
@@ -3,10 +3,10 @@
 
 import copy
 import json
-import mock
 import logging
 import datetime
 import unittest
+import unittest.mock as mock
 
 from flask import current_app
 from pdm.site.SiteService import SiteService
diff --git a/test/pdm/userservicedesk/test_HRClient.py b/test/pdm/userservicedesk/test_HRClient.py
index a2b5b66b..5932cb23 100644
--- a/test/pdm/userservicedesk/test_HRClient.py
+++ b/test/pdm/userservicedesk/test_HRClient.py
@@ -4,7 +4,7 @@
 
 import json
 import unittest
-import mock
+import unittest.mock as mock
 import datetime
 
 from pdm.userservicedesk.HRClient import HRClient
diff --git a/test/pdm/userservicedesk/test_HRService.py b/test/pdm/userservicedesk/test_HRService.py
index e9364663..698cae6b 100644
--- a/test/pdm/userservicedesk/test_HRService.py
+++ b/test/pdm/userservicedesk/test_HRService.py
@@ -2,7 +2,7 @@
 import os
 import time
 import unittest
-import mock
+import unittest.mock as mock
 import copy
 import datetime
 import smtplib
diff --git a/test/pdm/userservicedesk/test_TransferClient.py b/test/pdm/userservicedesk/test_TransferClient.py
index a42ff10a..7e34ad90 100644
--- a/test/pdm/userservicedesk/test_TransferClient.py
+++ b/test/pdm/userservicedesk/test_TransferClient.py
@@ -1,5 +1,5 @@
-import mock
 import unittest
+import unittest.mock as mock
 import datetime
 from pdm.userservicedesk.TransferClientFacade import TransferClientFacade
 from pdm.framework.FlaskWrapper import FlaskServer
diff --git a/test/pdm/utils/test_X509.py b/test/pdm/utils/test_X509.py
index 874f0417..d9c158a7 100644
--- a/test/pdm/utils/test_X509.py
+++ b/test/pdm/utils/test_X509.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 
 import os
-import mock
 import unittest
+import unittest.mock as mock
 from functools import partial
 
 from pdm.utils.X509 import X509Utils
diff --git a/test/pdm/utils/test_db.py b/test/pdm/utils/test_db.py
index ba3d8f87..9a7bc2d5 100644
--- a/test/pdm/utils/test_db.py
+++ b/test/pdm/utils/test_db.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 """ Test DB utils. """
 
-import mock
 import unittest
+import unittest.mock as mock
 
 from pdm.utils.db import managed_session
 
diff --git a/test/pdm/utils/test_lockfile.py b/test/pdm/utils/test_lockfile.py
index 6b71aa1b..0a11cd0f 100644
--- a/test/pdm/utils/test_lockfile.py
+++ b/test/pdm/utils/test_lockfile.py
@@ -2,9 +2,9 @@
 """ Test of utils lockfile module. """
 
 import os
-import mock
 import fcntl
 import unittest
+import unittest.mock as mock
 
 from pdm.utils.lockfile import PIDLockFile, AlreadyLockedError
 
diff --git a/test/pdm/utils/test_myproxy.py b/test/pdm/utils/test_myproxy.py
index 6ccda589..1d38b0b8 100644
--- a/test/pdm/utils/test_myproxy.py
+++ b/test/pdm/utils/test_myproxy.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 
 import os
-import mock
 import unittest
+import unittest.mock as mock
 
 from pdm.utils.myproxy import MyProxyUtils
 
diff --git a/test/pdm/web/test_WebPageService.py b/test/pdm/web/test_WebPageService.py
index 77dc975d..1ae223a9 100644
--- a/test/pdm/web/test_WebPageService.py
+++ b/test/pdm/web/test_WebPageService.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 
 import unittest
-import mock
+import unittest.mock as mock
 
 from pdm.web.WebPageService import WebPageService
 from pdm.framework.FlaskWrapper import FlaskServer
diff --git a/test/pdm/workqueue/scripts/test_stdout_dump_helper.py b/test/pdm/workqueue/scripts/test_stdout_dump_helper.py
index 70394913..2a3c1c68 100644
--- a/test/pdm/workqueue/scripts/test_stdout_dump_helper.py
+++ b/test/pdm/workqueue/scripts/test_stdout_dump_helper.py
@@ -2,7 +2,7 @@
 import unittest
 import logging
 
-import mock
+import unittest.mock as mock
 
 from pdm.workqueue.scripts import stdout_dump_helper
 
diff --git a/test/pdm/workqueue/test_Worker.py b/test/pdm/workqueue/test_Worker.py
index c65920b3..39632c5a 100644
--- a/test/pdm/workqueue/test_Worker.py
+++ b/test/pdm/workqueue/test_Worker.py
@@ -2,7 +2,7 @@
 """ Test Worker module. """
 import logging
 import unittest
-import mock
+import unittest.mock as mock
 
 from pdm.framework.FlaskWrapper import FlaskServer, jsonify
 from pdm.framework.RESTClient import RESTClientTest
diff --git a/test/pdm/workqueue/test_WorkqueueClient.py b/test/pdm/workqueue/test_WorkqueueClient.py
index 624cbcb8..f4345815 100644
--- a/test/pdm/workqueue/test_WorkqueueClient.py
+++ b/test/pdm/workqueue/test_WorkqueueClient.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 """ Test WorkqueueClient module. """
 import unittest
-import mock
+import unittest.mock as mock
 
 from pdm.framework.FlaskWrapper import FlaskServer, jsonify
 from pdm.framework.RESTClient import RESTClientTest
diff --git a/test/pdm/workqueue/test_WorkqueueService.py b/test/pdm/workqueue/test_WorkqueueService.py
index 382ad9d9..4dccfe15 100644
--- a/test/pdm/workqueue/test_WorkqueueService.py
+++ b/test/pdm/workqueue/test_WorkqueueService.py
@@ -3,7 +3,7 @@
 import json
 import unittest
 from textwrap import dedent
-import mock
+import unittest.mock as mock
 
 from pdm.framework.FlaskWrapper import FlaskServer
 from pdm.workqueue.WorkqueueDB import JobType, JobStatus, JobProtocol
diff --git a/tox.ini b/tox.ini
index 62ab4415..c4ab1622 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,6 @@ sitepackages=True
 # Standard unit testing + coverage
 [testenv:unit]
 deps=
-  mock
   pytest
   coverage
 commands=
@@ -26,7 +25,6 @@ commands=
 
 [testenv:lint]
 deps=
-  mock
   pylint
 commands=
   /bin/bash test/bin/run_pylint.sh