diff --git a/user_guide/installation/upgrading.html b/user_guide/installation/upgrading.html
index fa94a5c..9b745d1 100644
--- a/user_guide/installation/upgrading.html
+++ b/user_guide/installation/upgrading.html
@@ -60,6 +60,7 @@
 <p>Please read the upgrade notes corresponding to the version you are upgrading from.</p>
 
 <ul>
+<li><a href="upgrade_164.html">Upgrading from 1.6.3 to 1.6.4</a></li>
 <li><a href="upgrade_163.html">Upgrading from 1.6.2 to 1.6.3</a></li>
 <li><a href="upgrade_162.html">Upgrading from 1.6.1 to 1.6.2</a></li>
 <li><a href="upgrade_161.html">Upgrading from 1.6.0 to 1.6.1</a></li>