diff --git a/htdocs/install/mysql/migration/3.2.0-3.3.0.sql b/htdocs/install/mysql/migration/3.2.0-3.3.0.sql
index bf6229c859f..cecc2362265 100755
--- a/htdocs/install/mysql/migration/3.2.0-3.3.0.sql
+++ b/htdocs/install/mysql/migration/3.2.0-3.3.0.sql
@@ -746,3 +746,6 @@ insert into llx_accountingaccount (rowid, fk_pcg_version, pcg_type, pcg_subtype,
 -- Add discount in product supplier price
 ALTER TABLE llx_product_fournisseur_price ADD COLUMN remise_percent DOUBLE NOT NULL DEFAULT 0 AFTER quantity;
 ALTER TABLE llx_product_fournisseur_price ADD COLUMN remise DOUBLE NOT NULL DEFAULT 0 AFTER remise_percent; 
+
+-- Stock calculation on product
+UPDATE llx_product p SET p.stock= (SELECT SUM(ps.reel) FROM llx_product_stock ps WHERE ps.fk_product = p.rowid);
diff --git a/htdocs/product/stock/class/mouvementstock.class.php b/htdocs/product/stock/class/mouvementstock.class.php
index ea0a4aee05b..c95f8b9b3a3 100644
--- a/htdocs/product/stock/class/mouvementstock.class.php
+++ b/htdocs/product/stock/class/mouvementstock.class.php
@@ -193,7 +193,7 @@ class MouvementStock
 
 			if (! $error)
 			{
-				$sql = "UPDATE ".MAIN_DB_PREFIX."product SET pmp = ".$newpmp.", stock = stock + ".$qty;
+				$sql = "UPDATE ".MAIN_DB_PREFIX."product SET pmp = ".$newpmp.", stock = IFNULL(stock, 0) + ".$qty;
 				$sql.= " WHERE rowid = ".$fk_product;
 
 				dol_syslog("MouvementStock::_create sql=".$sql);