diff --git a/stock_available/models/product_product.py b/stock_available/models/product_product.py
index e9fe960e4..a22951f92 100644
--- a/stock_available/models/product_product.py
+++ b/stock_available/models/product_product.py
@@ -14,7 +14,7 @@ class ProductProduct(models.Model):
     """
     _inherit = 'product.product'
 
-    @api.one
+    @api.multi
     @api.depends('virtual_available')
     def _immediately_usable_qty(self):
         """No-op implementation of the stock available to promise.
@@ -23,7 +23,8 @@ class ProductProduct(models.Model):
 
         Must be overridden by another module that actually implement
         computations."""
-        self.immediately_usable_qty = self.virtual_available
+        for prod in self:
+            prod.immediately_usable_qty = prod.virtual_available
 
     immediately_usable_qty = fields.Float(
         digits=dp.get_precision('Product Unit of Measure'),
diff --git a/stock_available/models/product_template.py b/stock_available/models/product_template.py
index cdff1f35e..a7f1fcc4b 100644
--- a/stock_available/models/product_template.py
+++ b/stock_available/models/product_template.py
@@ -9,12 +9,15 @@ from openerp.addons import decimal_precision as dp
 class ProductTemplate(models.Model):
     _inherit = 'product.template'
 
-    @api.one
-    @api.depends('virtual_available')
+    @api.multi
+    @api.depends('product_variant_ids.immediately_usable_qty')
     def _immediately_usable_qty(self):
         """Compute the quantity using all the variants"""
-        self.immediately_usable_qty = sum(
-            [v.immediately_usable_qty for v in self.product_variant_ids])
+        for tmpl in self:
+            tmpl.immediately_usable_qty = sum(
+                v.immediately_usable_qty
+                for v in tmpl.product_variant_ids
+            )
 
     immediately_usable_qty = fields.Float(
         digits=dp.get_precision('Product Unit of Measure'),