diff --git a/actionpack/lib/action_view/helpers/atom_feed_helper.rb b/actionpack/lib/action_view/helpers/atom_feed_helper.rb
index 39c37b25dc8493ac3b248d122e9f0b718f424d18..73824dc1f845fd1c8f8a2fb55dfc62fc33f766e5 100644
--- a/actionpack/lib/action_view/helpers/atom_feed_helper.rb
+++ b/actionpack/lib/action_view/helpers/atom_feed_helper.rb
@@ -32,7 +32,7 @@ module AtomFeedHelper
       #   app/views/posts/index.atom.builder:
       #     atom_feed do |feed|
       #       feed.title("My great blog!")
-      #       feed.updated(@posts.first.created_at)
+      #       feed.updated(@posts[0].created_at) if @posts.length > 0
       #
       #       @posts.each do |post|
       #         feed.entry(post) do |entry|