application.rb

        Dir.glob(File.join(File.dirname(__FILE__), "../../../app/**/*_decorator*.rb")) do |c|
          Rails.configuration.cache_classes ? require(c) : load(c)
        end

Thank you, sir... didn't like the ../../.. bit, so I forked and used Rails.root.join() instead...

based on the 6-spaced indentation I'm assuming this goes inside class Application < Rails::Application

oops, it goes inside of that ^, but also inside of config.after_initialize {...}