diff --git a/htdocs/product/stock/product.php b/htdocs/product/stock/product.php
index 5929a46edb8..af12804aac5 100644
--- a/htdocs/product/stock/product.php
+++ b/htdocs/product/stock/product.php
@@ -1018,7 +1018,8 @@ if (!$variants) {
 	}
 } else {
 	// List of variants
-
+	include_once DOL_DOCUMENT_ROOT.'/variants/class/ProductCombination.class.php';
+	include_once DOL_DOCUMENT_ROOT.'/variants/class/ProductCombination2ValuePair.class.php';
 	$prodstatic = new Product($db);
 	$prodcomb = new ProductCombination($db);
 	$comb2val = new ProductCombination2ValuePair($db);