diff --git a/htdocs/expensereport/list.php b/htdocs/expensereport/list.php
index 5b633552380..873c3c97d9a 100644
--- a/htdocs/expensereport/list.php
+++ b/htdocs/expensereport/list.php
@@ -4,6 +4,7 @@
  * Copyright (C) 2004     	Eric Seigne          <eric.seigne@ryxeo.com>
  * Copyright (C) 2005-2009	Regis Houssin        <regis.houssin@capnetworks.com>
  * Copyright (C) 2015       Alexandre Spangaro   <aspangaro.dolibarr@gmail.com>
+ * Copyright (C) 2019       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
@@ -67,7 +68,7 @@ if (!$sortfield) $sortfield="d.date_debut";
 $id = GETPOST('id', 'int');
 
 $sall         = trim((GETPOST('search_all', 'alphanohtml')!='')?GETPOST('search_all', 'alphanohtml'):GETPOST('sall', 'alphanohtml'));
-$search_ref   = GETPOST('search_ref');
+$search_ref   = GETPOST('search_ref', 'alpha');
 $search_user  = GETPOST('search_user','int');
 $search_amount_ht = GETPOST('search_amount_ht','alpha');
 $search_amount_vat = GETPOST('search_amount_vat','alpha');