diff --git a/Gemfile b/Gemfile
index 8b19a8036f0..d23071e1f6d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -74,6 +74,7 @@ gem 'unf', require: false
 gem 'email_reply_trimmer', '~> 0.1'
 
 # Forked until https://github.com/toy/image_optim/pull/162 is merged
+# https://github.com/discourse/image_optim
 gem 'discourse_image_optim', require: 'image_optim'
 gem 'multi_json'
 gem 'mustache'