diff --git a/htdocs/contrat/class/contrat.class.php b/htdocs/contrat/class/contrat.class.php
index 51e56cd2f7d..f471ca649fa 100644
--- a/htdocs/contrat/class/contrat.class.php
+++ b/htdocs/contrat/class/contrat.class.php
@@ -1834,7 +1834,7 @@ class Contrat extends CommonObject
 /**
  *	Classe permettant la gestion des lignes de contrats
  */
-class ContratLigne
+class ContratLigne extends CommonObject
 {
 	var $db;							//!< To store db handler
 	var $error;							//!< To return error code (or message)