diff --git a/.mdl_style.rb b/.mdl_style.rb
index 7d1fa592c277d00d46a334963636d88e1d5eed23..e1530be24d7c2dbfe7826290f001e17042b7e324 100644
--- a/.mdl_style.rb
+++ b/.mdl_style.rb
@@ -2,7 +2,8 @@ all
 # our changelog does this, by design
 # exclude_rule 'MD003'
 # rule 'MD007', :indent => 3
-rule 'MD013', heading_line_length: 400
+# not working rule:
+# rule 'MD013', heading_line_length: 400
 # => doesn't work for style
 # rule 'MD029', :style => :ordered
 rule "MD029", style: "ordered"