diff --git a/.mdl_style.rb b/.mdl_style.rb
index 9e94bc07b747b0e7e4519fa68d917bd974c7fc8a..25532b124e52a0dd3d777ac597b7de2658b3d59c 100644
--- a/.mdl_style.rb
+++ b/.mdl_style.rb
@@ -2,7 +2,7 @@ all
 # our changelog does this, by design
 # exclude_rule 'MD003'
 # rule 'MD007', :indent => 3
-rule 'MD013', :heading_line_length => 90
+rule 'MD013', heading_line_length: "90"
 # => doesn't work for style
 # rule 'MD029', :style => :ordered
 rule "MD029", style: "ordered"