diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 4b6d4fef97..5ecad6bc04 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -201,9 +201,11 @@ module ActionDispatch
         self.resources_path_names = self.class.default_resources_path_names.dup
         self.controller_namespaces = Set.new
         self.default_url_options = {}
+
         self.request_class = request_class
-        self.valid_conditions = request_class.public_instance_methods.select{ |m| m != "id" }.map{ |m| m.to_sym }
-        self.valid_conditions += [:controller, :action]
+        self.valid_conditions = request_class.public_instance_methods.map { |m| m.to_sym }
+        self.valid_conditions.delete(:id)
+        self.valid_conditions.push(:controller, :action)
 
         @disable_clear_and_finalize = false
         clear!