diff --git a/ironic_inspector/firewall.py b/ironic_inspector/firewall.py
index ec5cff1c2..75b689c51 100644
--- a/ironic_inspector/firewall.py
+++ b/ironic_inspector/firewall.py
@@ -49,7 +49,7 @@ def _iptables(*args, **kwargs):
             LOG.debug('Ignoring failed iptables %(args)s: %(output)s',
                       {'args': args, 'output': output})
         else:
-            LOG.error(_LE('iptables %(iptables)s failed: %(exc)s') %
+            LOG.error(_LE('iptables %(iptables)s failed: %(exc)s'),
                       {'iptables': args, 'exc': output})
             raise
 
diff --git a/ironic_inspector/node_cache.py b/ironic_inspector/node_cache.py
index a427d67b6..361afc1f4 100644
--- a/ironic_inspector/node_cache.py
+++ b/ironic_inspector/node_cache.py
@@ -510,8 +510,8 @@ def find_node(**attributes):
         if not isinstance(value, list):
             value = [value]
 
-        LOG.debug('Trying to use %s of value %s for node look up'
-                  % (name, value))
+        LOG.debug('Trying to use %s of value %s for node look up',
+                  (name, value))
         value_list = []
         for v in value:
             value_list.append("name='%s' AND value='%s'" % (name, v))
diff --git a/ironic_inspector/process.py b/ironic_inspector/process.py
index 5f8c7539e..926debccc 100644
--- a/ironic_inspector/process.py
+++ b/ironic_inspector/process.py
@@ -315,7 +315,7 @@ def _finish_set_ipmi_credentials(ironic, node, node_info, introspection_data,
             ironic.node.get_boot_device(node_info.uuid)
         except Exception as exc:
             LOG.info(_LI('Waiting for credentials update, attempt %(attempt)d '
-                         'current error is %(exc)s') %
+                         'current error is %(exc)s'),
                      {'attempt': attempt, 'exc': exc},
                      node_info=node_info, data=introspection_data)
             eventlet.greenthread.sleep(_CREDENTIALS_WAIT_PERIOD)
@@ -338,7 +338,7 @@ def _finish(ironic, node_info, introspection_data, power_off=True):
             if node_info.node().provision_state == 'enroll':
                 LOG.info(_LI("Failed to power off the node in"
                              "'enroll' state, ignoring; error was "
-                             "%s") % exc, node_info=node_info,
+                             "%s"), exc, node_info=node_info,
                          data=introspection_data)
             else:
                 msg = (_('Failed to power off node %(node)s, check '
diff --git a/test-requirements.txt b/test-requirements.txt
index 1766e0f4b..69a1b29c2 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 coverage>=4.0 # Apache-2.0
 doc8 # Apache-2.0
-hacking<0.12,>=0.11.0 # Apache-2.0
+hacking<0.13,>=0.12.0 # Apache-2.0
 mock>=2.0 # BSD
 sphinx!=1.3b1,<1.4,>=1.2.1 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
diff --git a/tox.ini b/tox.ini
index 2a63b4428..d31a4ed13 100644
--- a/tox.ini
+++ b/tox.ini
@@ -47,6 +47,10 @@ commands = oslo-config-generator --config-file config-generator.conf
 
 [flake8]
 max-complexity=15
+# [H106] Don’t put vim configuration in source files.
+# [H203] Use assertIs(Not)None to check for None.
+# [H904] Delay string interpolations at logging calls.
+enable-extensions=H106,H203,H904
 
 [hacking]
 import_exceptions = ironicclient.exceptions,ironic_inspector.common.i18n