diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index 130ba617869fcc1ddee1bbfb55bc3a364c5f852c..8af94551cf153c3f4eb27da8e922651298d4d26e 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -3,6 +3,7 @@
 require 'active_support/core_ext/string/filters'
 require 'active_support/rescuable'
 require 'action_dispatch/http/upload'
+require 'rack/test'
 require 'stringio'
 require 'set'