diff --git a/actionpack/lib/action_dispatch/http/mime_negotiation.rb b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
index 6bf4e652d3..3764398afa 100644
--- a/actionpack/lib/action_dispatch/http/mime_negotiation.rb
+++ b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
@@ -152,6 +152,8 @@ module ActionDispatch
       end
 
       private
+        # We use normal content negotiation unless you include */* in your list,
+        # in which case we assume you're a browser and send HTML.
         BROWSER_LIKE_ACCEPTS = /,\s*\*\/\*|\*\/\*\s*,/
 
         def params_readable? # :doc: