diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 0f33b40a13..98da7e2b4a 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -166,7 +166,7 @@ module Rails
       paths.app.controllers.to_a.each do |load_path|
         load_path = File.expand_path(load_path)
         Dir["#{load_path}/*/**/*_controller.rb"].collect do |path|
-          namespace = File.dirname(path).sub(/#{load_path}\/?/, '')
+          namespace = File.dirname(path).sub(/#{Regexp.escape(load_path)}\/?/, '')
           app.routes.controller_namespaces << namespace unless namespace.empty?
         end
       end