diff --git a/ChangeLog b/ChangeLog
index 338a1406b8e..0978f65863b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -41,6 +41,7 @@ Fix: [ bug #1240 ] traduction.
 Fix: [ bug #1238 ] When creating accompte with a %, free product are used for calculation.
 Fix: [ bug #1280 ] service with not end of date was tagged as expired.
 Fix: [ bug #1295 ] Error when creating an agenda extrafield with a number as reference
+Fix: [ bug #1306 ] Fatal error when adding an external calendar
 New: Added es_CL language
 
 ***** ChangeLog for 3.5 compared to 3.4.* *****
diff --git a/htdocs/admin/agenda_extsites.php b/htdocs/admin/agenda_extsites.php
index 4bb3cb8c4f3..b133485f866 100644
--- a/htdocs/admin/agenda_extsites.php
+++ b/htdocs/admin/agenda_extsites.php
@@ -1,6 +1,6 @@
 <?php
 /* Copyright (C) 2008-2011 Laurent Destailleur  <eldy@users.sourceforge.net>
- * Copyright (C) 2011-2013 Juanjo Menent        <jmenent@2byte.es>
+ * Copyright (C) 2011-2014 Juanjo Menent        <jmenent@2byte.es>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -28,6 +28,7 @@ require_once DOL_DOCUMENT_ROOT.'/core/class/html.formadmin.class.php';
 require_once DOL_DOCUMENT_ROOT.'/core/class/html.formother.class.php';
 require_once DOL_DOCUMENT_ROOT.'/core/lib/agenda.lib.php';
 require_once DOL_DOCUMENT_ROOT.'/core/lib/date.lib.php';
+require_once DOL_DOCUMENT_ROOT.'/core/lib/files.lib.php';
 
 if (!$user->admin)
     accessforbidden();