diff --git a/ironic/db/sqlalchemy/alembic/versions/5674c57409b9_replace_nostate_with_available.py b/ironic/db/sqlalchemy/alembic/versions/5674c57409b9_replace_nostate_with_available.py
index bdae6788ea..38c2343e23 100644
--- a/ironic/db/sqlalchemy/alembic/versions/5674c57409b9_replace_nostate_with_available.py
+++ b/ironic/db/sqlalchemy/alembic/versions/5674c57409b9_replace_nostate_with_available.py
@@ -24,7 +24,7 @@ down_revision = '242cc6a923b3'
 
 from alembic import op
 from sqlalchemy import String
-from sqlalchemy.sql import table, column
+from sqlalchemy.sql import table, column, null
 
 node = table('nodes',
              column('uuid', String(36)),
@@ -41,7 +41,7 @@ AVAILABLE = 'available'
 def upgrade():
     op.execute(
         node.update().where(
-            node.c.provision_state == None).values(
+            node.c.provision_state == null()).values(
                 {'provision_state': op.inline_literal(AVAILABLE)}))
 
 
diff --git a/ironic/db/sqlalchemy/api.py b/ironic/db/sqlalchemy/api.py
index 76c51f3cee..12fb55edf8 100644
--- a/ironic/db/sqlalchemy/api.py
+++ b/ironic/db/sqlalchemy/api.py
@@ -29,6 +29,7 @@ from oslo_utils import strutils
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
 from sqlalchemy.orm.exc import NoResultFound
+from sqlalchemy import sql
 
 from ironic.common import exception
 from ironic.common.i18n import _
@@ -159,14 +160,14 @@ class Connection(api.Connection):
             query = query.filter_by(chassis_id=chassis_obj.id)
         if 'associated' in filters:
             if filters['associated']:
-                query = query.filter(models.Node.instance_uuid != None)
+                query = query.filter(models.Node.instance_uuid != sql.null())
             else:
-                query = query.filter(models.Node.instance_uuid == None)
+                query = query.filter(models.Node.instance_uuid == sql.null())
         if 'reserved' in filters:
             if filters['reserved']:
-                query = query.filter(models.Node.reservation != None)
+                query = query.filter(models.Node.reservation != sql.null())
             else:
-                query = query.filter(models.Node.reservation == None)
+                query = query.filter(models.Node.reservation == sql.null())
         if 'maintenance' in filters:
             query = query.filter_by(maintenance=filters['maintenance'])
         if 'driver' in filters:
diff --git a/tox.ini b/tox.ini
index b942a46791..933901ab5b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -59,8 +59,7 @@ setenv = PYTHONHASHSEED=0
 commands = {posargs}
 
 [flake8]
-# E711: ignored because it is normal to use "column == None" in sqlalchemy
-ignore = E129,E711
+ignore = E129
 exclude =  .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,tools
 max-complexity=17