diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 52f3fd1610..bb689beed9 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -179,6 +179,7 @@ module ActionDispatch
 
                 url_for(options)
               end
+              protected :#{selector}
             END_EVAL
             helpers << selector
           end