diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index c37d92a5b61..b9dd611684a 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -781,7 +781,7 @@ class Product extends CommonObject
 	 *
 	 * @var array<string,array<int,array{0:int,1:float,2:int,3:string,4:int,5:string}>>
 	 */
-	public $sousprods;
+	public $sousprods = array();
 
 	/**
 	 * @var array<int,array{id:int,id_parent:int,ref:string,nb:int,nb_total:int,stock:float,stock_alert:float,label:string,fullpath:string,type:int,desiredstick:float,level:int,incdec:int<0,1>,entity:CommonObject}> Path of subproducts. Build from ->sousprods with get_arbo_each_prod()