diff --git a/addons/userrights/userrightsmatrix.class.inc.php b/addons/userrights/userrightsmatrix.class.inc.php
index ab3d3c132..9d7dd15d3 100644
--- a/addons/userrights/userrightsmatrix.class.inc.php
+++ b/addons/userrights/userrightsmatrix.class.inc.php
@@ -140,7 +140,7 @@ class UserRightsMatrix extends UserRightsAddOnAPI
 	);
 
 	// Installation: create the very first user
-	public function CreateAdministrator($sAdminUser, $sAdminPwd, $sLanguage)
+	public function CreateAdministrator($sAdminUser, $sAdminPwd, $sLanguage = 'EN US')
 	{
 		// Maybe we should check that no other user with userid == 0 exists
 		$oUser = new UserRightsMatrixUsers();