diff --git a/railties/guides/source/engines.textile b/railties/guides/source/engines.textile
index e531bc7507ae46e7bdda5958bad2e757c5496cdd..db2db05e571f35879bc9af0a0b0d4b5bbc861e56 100644
--- a/railties/guides/source/engines.textile
+++ b/railties/guides/source/engines.textile
@@ -289,4 +289,4 @@ h3. Overriding engine functionality
 TODO: Cover how to override engine functionality in the engine, such as controllers and views.
 IDEA: I like Devise's +devise :controllers => { "sessions" => "sessions" }+ idea. Perhaps we could incorporate that into the guide?
 TODO: Mention how to use assets within an engine?
-
+TODO: Mention how to depend on external gems, like RedCarpet.