diff --git a/lib/review/htmlutils.rb b/lib/review/htmlutils.rb
index 1938494f8..cb9273065 100644
--- a/lib/review/htmlutils.rb
+++ b/lib/review/htmlutils.rb
@@ -107,7 +107,7 @@ def highlight_rouge(ops)
       raise "unknown lexer #{lexer}" unless lexer
 
       #formatter = Rouge::Formatters::HTML.new()
-      formatter = Rouge::Formatters::HTML.new(css_class: 'highlight')
+      formatter = Rouge::Formatters::HTML.new(:css_class => 'highlight')
       #formatter = Rouge::Formatters::HTMLLegacy.new(:css_class => "highlight #{lexer.tag}")
       #formatter = Rouge::Formatters::HTMLPygments.new(Rouge::Formatters::HTML.new, "highlight #{lexer.tag}")
       #formatter = Rouge::Formatters::HTMLInline.new(Rouge::Themes::Colorful.new)