diff --git a/config/initializers/gollum.rb b/config/initializers/gollum.rb
index 2fd47a3f4d3..f1066f83dd9 100644
--- a/config/initializers/gollum.rb
+++ b/config/initializers/gollum.rb
@@ -1,3 +1,7 @@
+# WARNING changes in this file must be manually propagated to gitaly-ruby.
+#
+# https://gitlab.com/gitlab-org/gitaly/blob/master/ruby/lib/gitlab/gollum.rb
+
 module Gollum
   GIT_ADAPTER = "rugged".freeze
 end