diff --git a/tox.ini b/tox.ini
index bf61d79..e18bf06 100644
--- a/tox.ini
+++ b/tox.ini
@@ -54,11 +54,9 @@ commands = sphinx-build -a -E -b html releasenotes/source releasenotes/build/htm
 # H803 skipped on purpose per list discussion.
 # H404  multi line docstring should start with a summary
 # H405 multi line docstring summary not separated with an empty line
-## TODO(ruhe) following checks should be fixed
-# E721 do not compare types, use 'isinstance()'
 # W503 line break before binary operator
 # W504 line break after binary operator
 show-source = True
-ignore = E721,H404,H405,H803,W503,W504
+ignore = H404,H405,H803,W503,W504
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build