diff --git a/quantum/plugins/midonet/midonet_lib.py b/quantum/plugins/midonet/midonet_lib.py
index 9ad6b94ccf..8e2c1dfda0 100644
--- a/quantum/plugins/midonet/midonet_lib.py
+++ b/quantum/plugins/midonet/midonet_lib.py
@@ -903,7 +903,7 @@ class MidoClient:
         port_group_id = None
 
         # handle source
-        if not remote_ip_prefix is None:
+        if remote_ip_prefix is not None:
             nw_src_address, nw_src_length = remote_ip_prefix.split('/')
         elif not remote_group_id is None:  # security group as a srouce
             source_pg = self.pg_manager.get_for_sg(tenant_id, remote_group_id)
diff --git a/quantum/policy.py b/quantum/policy.py
index 05e11ec103..610e4c5b85 100644
--- a/quantum/policy.py
+++ b/quantum/policy.py
@@ -99,7 +99,7 @@ def _set_rules(data):
                 for actual_policy in ['_'.join(item) for item in
                                       itertools.product(new_actions,
                                                         new_policies)]:
-                    if not actual_policy in policies:
+                    if actual_policy not in policies:
                         # New policy, same rule
                         LOG.info(_("Inserting policy:%(new_policy)s in place "
                                    "of deprecated policy:%(old_policy)s"),
diff --git a/quantum/tests/unit/nicira/fake_nvpapiclient.py b/quantum/tests/unit/nicira/fake_nvpapiclient.py
index d29d237d06..40ac6e853d 100644
--- a/quantum/tests/unit/nicira/fake_nvpapiclient.py
+++ b/quantum/tests/unit/nicira/fake_nvpapiclient.py
@@ -260,7 +260,7 @@ class FakeClient:
         return fake_gwservice
 
     def _build_relation(self, src, dst, resource_type, relation):
-        if not relation in self.MANAGED_RELATIONS[resource_type]:
+        if relation not in self.MANAGED_RELATIONS[resource_type]:
             return  # Relation is not desired in output
         if not '_relations' in src or not src['_relations'].get(relation):
             return  # Item does not have relation
diff --git a/tox.ini b/tox.ini
index 5148995340..d111aeeb89 100644
--- a/tox.ini
+++ b/tox.ini
@@ -36,8 +36,7 @@ commands = {posargs}
 # H301 one import per line
 # H302 import only modules
 # TODO(marun) H404 multi line docstring should start with a summary
-# TODO(marun) H901,902 use the not operator inline for clarity
-ignore = E711,E712,E125,H301,H302,H404,H901,H902
+ignore = E711,E712,E125,H301,H302,H404
 show-source = true
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,tools