diff --git a/doc/installation.rst b/doc/installation.rst
index 7003d51660..14ecd9c300 100644
--- a/doc/installation.rst
+++ b/doc/installation.rst
@@ -12,6 +12,7 @@ Prerequisites
  * Optional: simplejson (http://undefined.org/python/#simplejson)
  * Optional: pytz (http://pytz.sourceforge.net/)
  * Optional: cdecimal (http://www.bytereef.org/mpdecimal/index.html)
+ * Optional: GooCalendar (http://code.google.com/p/goocalendar/)
 
 Installation
 ------------