diff --git a/htdocs/admin/tools/listevents.php b/htdocs/admin/tools/listevents.php
index b894920d34e..31287cbbb8a 100644
--- a/htdocs/admin/tools/listevents.php
+++ b/htdocs/admin/tools/listevents.php
@@ -68,6 +68,7 @@ $search_user = GETPOST("search_user", "alpha");
 $search_desc = GETPOST("search_desc", "alpha");
 $search_ua   = GETPOST("search_ua", "restricthtml");
 $search_prefix_session = GETPOST("search_prefix_session", "restricthtml");
+$optioncss = GETPOST("optioncss", "aZ"); // Option for the css output (always '' except when 'print')
 
 $now = dol_now();
 $nowarray = dol_getdate($now);
@@ -245,7 +246,7 @@ if ($result) {
 	if ($limit > 0 && $limit != $conf->liste_limit) {
 		$param .= '&limit='.urlencode($limit);
 	}
-	if (!empty($optioncss)) {
+	if ($optioncss != '') {
 		$param .= '&optioncss='.urlencode($optioncss);
 	}
 	if ($search_code) {