diff --git a/lib/tasks/gitlab/backup.rake b/lib/tasks/gitlab/backup.rake
index 99e84f62c66..0230fbb010b 100644
--- a/lib/tasks/gitlab/backup.rake
+++ b/lib/tasks/gitlab/backup.rake
@@ -79,6 +79,8 @@ namespace :gitlab do
 
     def configure_cron_mode
       if ENV['CRON']
+        # We need an object we can say 'puts' and 'print' to; let's use a
+        # StringIO.
         require 'stringio'
         $progress = StringIO.new
       else