diff --git a/core/log.class.inc.php b/core/log.class.inc.php
index dfb950e585..7efd61ad67 100644
--- a/core/log.class.inc.php
+++ b/core/log.class.inc.php
@@ -682,7 +682,7 @@ abstract class LogAPI
 	{
 		$oConnectedUser = UserRights::GetUserObject();
 		if (is_null($oConnectedUser)) {
-			return 'null';
+			return '';
 		}
 
 		return $oConnectedUser->GetKey();