diff --git a/actionpack/test/controller/flash_hash_test.rb b/actionpack/test/controller/flash_hash_test.rb
index 761b3f2748..1f02e392d6 100644
--- a/actionpack/test/controller/flash_hash_test.rb
+++ b/actionpack/test/controller/flash_hash_test.rb
@@ -1,3 +1,5 @@
+# Upstream FlashHash tests from:
+# https://github.com/rails/rails/blob/a6ce984b49519de7701aa13d04300c9d03cf8f72/actionpack/test/controller/flash_hash_test.rb
 require 'abstract_unit'
 
 module ActionDispatch