Index: flake8-3.7.5/tests/integration/test_checker.py
===================================================================
--- flake8-3.7.5.orig/tests/integration/test_checker.py
+++ flake8-3.7.5/tests/integration/test_checker.py
@@ -1,5 +1,8 @@
 """Integration tests for the checker submodule."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import checker
Index: flake8-3.7.5/tests/unit/test_application.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_application.py
+++ flake8-3.7.5/tests/unit/test_application.py
@@ -1,7 +1,10 @@
 """Tests for the Application class."""
 import optparse
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.main import application as app
Index: flake8-3.7.5/tests/unit/test_base_formatter.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_base_formatter.py
+++ flake8-3.7.5/tests/unit/test_base_formatter.py
@@ -1,7 +1,10 @@
 """Tests for the BaseFormatter object."""
 import optparse
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import style_guide
Index: flake8-3.7.5/tests/unit/test_checker_manager.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_checker_manager.py
+++ flake8-3.7.5/tests/unit/test_checker_manager.py
@@ -1,7 +1,10 @@
 """Tests for the Manager object for FileCheckers."""
 import errno
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import checker
Index: flake8-3.7.5/tests/unit/test_config_file_finder.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_config_file_finder.py
+++ flake8-3.7.5/tests/unit/test_config_file_finder.py
@@ -4,7 +4,10 @@ import configparser
 import os
 import sys
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.options import config
Index: flake8-3.7.5/tests/unit/test_debug.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_debug.py
+++ flake8-3.7.5/tests/unit/test_debug.py
@@ -1,6 +1,9 @@
 """Tests for our debugging module."""
 import entrypoints
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.main import debug
Index: flake8-3.7.5/tests/unit/test_file_checker.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_file_checker.py
+++ flake8-3.7.5/tests/unit/test_file_checker.py
@@ -1,5 +1,8 @@
 """Unit tests for the FileChecker class."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 import flake8
Index: flake8-3.7.5/tests/unit/test_file_processor.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_file_processor.py
+++ flake8-3.7.5/tests/unit/test_file_processor.py
@@ -2,7 +2,10 @@
 import ast
 import tokenize
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import processor
Index: flake8-3.7.5/tests/unit/test_get_local_plugins.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_get_local_plugins.py
+++ flake8-3.7.5/tests/unit/test_get_local_plugins.py
@@ -1,5 +1,8 @@
 """Tests for get_local_plugins."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 
 from flake8.options import config
 
Index: flake8-3.7.5/tests/unit/test_git.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_git.py
+++ flake8-3.7.5/tests/unit/test_git.py
@@ -1,5 +1,8 @@
 """Tests around functionality in the git integration."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.main import git
Index: flake8-3.7.5/tests/unit/test_legacy_api.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_legacy_api.py
+++ flake8-3.7.5/tests/unit/test_legacy_api.py
@@ -1,5 +1,8 @@
 """Tests for Flake8's legacy API."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.api import legacy as api
Index: flake8-3.7.5/tests/unit/test_merged_config_parser.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_merged_config_parser.py
+++ flake8-3.7.5/tests/unit/test_merged_config_parser.py
@@ -1,7 +1,10 @@
 """Unit tests for flake8.options.config.MergedConfigParser."""
 import os
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.options import config
Index: flake8-3.7.5/tests/unit/test_option.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_option.py
+++ flake8-3.7.5/tests/unit/test_option.py
@@ -1,5 +1,8 @@
 """Unit tests for flake8.options.manager.Option."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8.options import manager
Index: flake8-3.7.5/tests/unit/test_option_manager.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_option_manager.py
+++ flake8-3.7.5/tests/unit/test_option_manager.py
@@ -2,7 +2,10 @@
 import optparse
 import os
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import utils
Index: flake8-3.7.5/tests/unit/test_plugin.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_plugin.py
+++ flake8-3.7.5/tests/unit/test_plugin.py
@@ -1,7 +1,10 @@
 """Tests for flake8.plugins.manager.Plugin."""
 import optparse
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import exceptions
Index: flake8-3.7.5/tests/unit/test_plugin_manager.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_plugin_manager.py
+++ flake8-3.7.5/tests/unit/test_plugin_manager.py
@@ -1,5 +1,8 @@
 """Tests for flake8.plugins.manager.PluginManager."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 
 from flake8.plugins import manager
 
Index: flake8-3.7.5/tests/unit/test_plugin_type_manager.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_plugin_type_manager.py
+++ flake8-3.7.5/tests/unit/test_plugin_type_manager.py
@@ -1,7 +1,10 @@
 """Tests for flake8.plugins.manager.PluginTypeManager."""
 import sys
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import exceptions
Index: flake8-3.7.5/tests/unit/test_style_guide.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_style_guide.py
+++ flake8-3.7.5/tests/unit/test_style_guide.py
@@ -1,7 +1,10 @@
 """Tests for the flake8.style_guide.StyleGuide class."""
 import optparse
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import statistics
Index: flake8-3.7.5/tests/unit/test_utils.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_utils.py
+++ flake8-3.7.5/tests/unit/test_utils.py
@@ -1,7 +1,10 @@
 """Tests for flake8's utils module."""
 import os
 
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import exceptions
Index: flake8-3.7.5/tests/unit/test_violation.py
===================================================================
--- flake8-3.7.5.orig/tests/unit/test_violation.py
+++ flake8-3.7.5/tests/unit/test_violation.py
@@ -1,5 +1,8 @@
 """Tests for the flake8.style_guide.Violation class."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 import pytest
 
 from flake8 import style_guide
Index: flake8-3.7.5/setup.py
===================================================================
--- flake8-3.7.5.orig/setup.py
+++ flake8-3.7.5/setup.py
@@ -11,6 +11,12 @@ sys.path.insert(0, os.path.join(os.path.
 
 import flake8
 
+PY2 = sys.version_info[0] == 2
+tests_require = ['pytest']
+
+if PY2:
+    tests_require.append('mock >= 2.0.0')
+
 
 # NOTE(sigmavirus24): When updating these requirements, update them in
 # setup.cfg as well.
@@ -147,4 +153,5 @@ setuptools.setup(
         "Topic :: Software Development :: Libraries :: Python Modules",
         "Topic :: Software Development :: Quality Assurance",
     ],
+    tests_require=tests_require,
 )
Index: flake8-3.7.5/tests/integration/test_main.py
===================================================================
--- flake8-3.7.5.orig/tests/integration/test_main.py
+++ flake8-3.7.5/tests/integration/test_main.py
@@ -1,5 +1,8 @@
 """Integration tests for the main entrypoint of flake8."""
-import mock
+try:
+    import unittest.mock as mock
+except ImportError:
+    import mock
 
 from flake8 import utils
 from flake8.main import application