diff --git a/Gemfile b/Gemfile
index 5e7ea6b3789..dcbcddfcce6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -78,6 +78,10 @@ else
 end
 gem 'rails-observers'
 
+# Rails 4.1.6+ will relax the mail gem version requirement to `~> 2.5, >= 2.5.4`.
+# However, mail gem 2.6.x currently does not work with discourse because of the
+# reference to `Mail::RFC2822Parser` in `lib/email.rb`. This ensure discourse
+# would continue to work with Rails 4.1.6+ when it is released.
 gem 'mail', '~> 2.5.4'
 
 #gem 'redis-rails'