diff --git a/tox.ini b/tox.ini
index 41e893c..f1b5b86 100644
--- a/tox.ini
+++ b/tox.ini
@@ -59,7 +59,11 @@
 enable-extensions = H106,H203,H904
 show-source = True
 # E123, E125 skipped as they are invalid PEP-8.
-ignore = E123,E125
+#
+# H405 is another one that is good as a guideline, but sometimes
+# multiline doc strings just don't have a natural summary
+# line. Rejecting code for this reason is wrong.
+ignore = E123,E125,H405
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build