diff --git a/tox.ini b/tox.ini
index 49811886..6ced3da8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -55,7 +55,10 @@ commands = sphinx-build -a -E -d releasenotes/build/doctrees -b html releasenote
 [flake8]
 builtins = _
 exclude = .venv,.git,.tox,dist,doc,*.egg
-# [H904] Delay string interpolations at logging calls.
-enable-extensions=H904
+# H203: Use assertIs(Not)None to check for None
+# H204: Use assert(Not)Equal()
+# H205: Use assert{Greater,Less}[Equal]
+# H904: Delay string interpolations at logging calls
+enable-extensions = H203,H204,H205,H904
 # W504 line break after binary operator
 ignore = W504