diff --git a/htdocs/product/class/api_products.class.php b/htdocs/product/class/api_products.class.php
index 7b19739d10e..a964b63799b 100644
--- a/htdocs/product/class/api_products.class.php
+++ b/htdocs/product/class/api_products.class.php
@@ -462,8 +462,8 @@ class Products extends DolibarrApi
 
 		$childsArbo = $this->product->getChildsArbo($id, 1);
 
-		$keys = ['rowid','qty', 'fk_product_type', 'label', 'incdec','ref'];
-		$childs = [];
+		$keys = array('rowid','qty', 'fk_product_type', 'label', 'incdec','ref');
+		$childs = array();
 		foreach ($childsArbo as $values) {
 			$childs[] = array_combine($keys, $values);
 		}