diff --git a/site/_docs/upgrading/2-to-3.md b/site/_docs/upgrading/2-to-3.md
index 330228de..e6fb2366 100644
--- a/site/_docs/upgrading/2-to-3.md
+++ b/site/_docs/upgrading/2-to-3.md
@@ -123,4 +123,8 @@ date: 2016-02-06 19:32:10 -0800
 ---
 {% endhighlight %}
 
+### My categories have stopped working!
+
+If you organized your categories as  `/_posts/code/2008-12-24-closures.md`, you will need to restructure your directories to put the categories _above_ the `_posts` directories, as follows: `/code/_posts/2008-12-24-closures.md`.
+
 _Did we miss something? Please click "Improve this page" above and add a section. Thanks!_