diff --git a/railties/lib/rails/rack/debugger.rb b/railties/lib/rails/rack/debugger.rb
index 0a7b405553..93a743a747 100644
--- a/railties/lib/rails/rack/debugger.rb
+++ b/railties/lib/rails/rack/debugger.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/kernel/requires'
+
 module Rails
   module Rack
     class Debugger