diff --git a/main/inc/lib/display.lib.php b/main/inc/lib/display.lib.php
index 5c8f06d767..4e6a8f46fc 100644
--- a/main/inc/lib/display.lib.php
+++ b/main/inc/lib/display.lib.php
@@ -473,7 +473,7 @@ class Display {
 	 * page title)
 	 * @param string $help
 	 */
-	function display_header($tool_name, $help = NULL)
+	function display_header($tool_name='', $help = NULL)
 	{
 		$nameTools = $tool_name;
 		global $_plugins;