diff --git a/user_guide/installation/upgrade_150.html b/user_guide/installation/upgrade_150.html
index b532073..e757d35 100644
--- a/user_guide/installation/upgrade_150.html
+++ b/user_guide/installation/upgrade_150.html
@@ -97,8 +97,14 @@
</pre>
+<h2>Step 3: Update your main index.php file</h2>
-<h2>Step 3: Update your user guide</h2>
+<p>If you are running a stock <dfn>index.php</dfn> file simply replace your version with the new one. If you are running one with
+internal modifications, open it and add this line of code near the bottom:</p>
+
+<code>define('FCPATH', __FILE__);</code>
+
+<h2>Step 4: Update your user guide</h2>
<p>Please also replace your local copy of the user guide with the new version.</p>