diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index 9b8fea19e5f..71ecd3f75d1 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -186,6 +186,12 @@ abstract class CommonObject
 	 */
 	public $projet;
 
+	/**
+	 * @deprecated
+	 * @see fk_project
+	 */
+	public $fk_projet;
+
 	/**
 	 * @var Contact a related contact
 	 * @see fetch_contact()