diff --git a/actionpack/lib/action_dispatch/http/mime_type.rb b/actionpack/lib/action_dispatch/http/mime_type.rb
index 047a17937a6ae..7e585aa244edf 100644
--- a/actionpack/lib/action_dispatch/http/mime_type.rb
+++ b/actionpack/lib/action_dispatch/http/mime_type.rb
@@ -45,7 +45,7 @@ def fetch(type)
   #
   #       respond_to do |format|
   #         format.html
-  #         format.ics { render text: @post.to_ics, mime_type: Mime::Type["text/calendar"]  }
+  #         format.ics { render text: @post.to_ics, mime_type: Mime::Type.lookup("text/calendar")  }
   #         format.xml { render xml: @post }
   #       end
   #     end