diff --git a/guides/rails_guides/textile_extensions.rb b/guides/rails_guides/textile_extensions.rb
index 4677fae504..0a002a785f 100644
--- a/guides/rails_guides/textile_extensions.rb
+++ b/guides/rails_guides/textile_extensions.rb
@@ -1,5 +1,11 @@
 require 'active_support/core_ext/object/inclusion'
 
+module RedCloth::Formatters::HTML
+  def emdash(opts)
+    "--"
+  end
+end
+
 module RailsGuides
   module TextileExtensions
     def notestuff(body)