diff --git a/mistral/tests/unit/lang/v2/test_workbook.py b/mistral/tests/unit/lang/v2/test_workbook.py
index fcf439f74..d74f6dffc 100644
--- a/mistral/tests/unit/lang/v2/test_workbook.py
+++ b/mistral/tests/unit/lang/v2/test_workbook.py
@@ -428,8 +428,7 @@ class WorkbookSpecValidation(base.WorkbookSpecValidationTestCase):
 
         for valid in valid_names:
             result = re.match(workbook.NON_VERSION_WORD_REGEX, valid)
-            self.assertNotEqual(
-                None,
+            self.assertIsNotNone(
                 result,
                 "Expected match for: {}".format(valid)
             )
@@ -440,8 +439,7 @@ class WorkbookSpecValidation(base.WorkbookSpecValidationTestCase):
 
         for invalid in invalid_names:
             result = re.match(workbook.NON_VERSION_WORD_REGEX, invalid)
-            self.assertEqual(
-                None,
+            self.assertIsNone(
                 result,
                 "Didn't expected match for: {}".format(invalid)
             )
diff --git a/mistral/tests/unit/rpc/kombu/test_kombu_listener.py b/mistral/tests/unit/rpc/kombu/test_kombu_listener.py
index f3f08d985..53f42df03 100644
--- a/mistral/tests/unit/rpc/kombu/test_kombu_listener.py
+++ b/mistral/tests/unit/rpc/kombu/test_kombu_listener.py
@@ -65,9 +65,8 @@ class KombuListenerTestCase(base.KombuTestCase):
 
         self.listener.remove_listener(correlation_id)
 
-        self.assertEqual(
-            self.listener._results.get(correlation_id),
-            None
+        self.assertIsNone(
+            self.listener._results.get(correlation_id)
         )
 
     def test_remove_listener_correlation_id_not_in_results(self):
diff --git a/tox.ini b/tox.ini
index b05caa27b..062bda058 100644
--- a/tox.ini
+++ b/tox.ini
@@ -75,6 +75,9 @@ whitelist_externals = rm
 ignore = D100,D101,D102,D103,D104,D105,D200,D203,D202,D204,D205,D208,D400,D401
 show-source = true
 builtins = _
+# [H106] Don't put vim configuration in source files.
+# [H203] Use assertIs(Not)None to check for None.
+enable-extensions = H106,H203
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,tools,scripts
 
 [hacking]