diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index 34d538675b9d417f4d40dfbe4722c46649fdcfb5..7cf9079fc0cd9725a30fa726daa75cb6651e5026 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -2856,7 +2856,7 @@ class Product extends CommonObject
 
 		$sql = 'INSERT INTO '.MAIN_DB_PREFIX.'product_association (fk_product_pere, fk_product_fils, qty)';
 		$sql.= " SELECT ".$toId.", fk_product_fils, qty FROM ".MAIN_DB_PREFIX."product_association";
-		$sql.= " WHERE fk_product_pere = '".$fromId."'";
+		$sql.= " WHERE fk_product_pere = ".$fromId;
 
 		dol_syslog(get_class($this).'::clone_association', LOG_DEBUG);
 		if (! $this->db->query($sql))