diff --git a/stock_available/__openerp__.py b/stock_available/__openerp__.py
index 14dcb7397..f5748a838 100644
--- a/stock_available/__openerp__.py
+++ b/stock_available/__openerp__.py
@@ -4,7 +4,7 @@
 
 {
     'name': 'Stock available to promise',
-    'version': '9.0.1.0.0',
+    'version': '9.0.1.0.1',
     "author": "Numérigraphe, Sodexis, Odoo Community Association (OCA)",
     'category': 'Warehouse',
     'depends': ['stock'],
diff --git a/stock_available/models/product_product.py b/stock_available/models/product_product.py
index a22951f92..e76a67ee6 100644
--- a/stock_available/models/product_product.py
+++ b/stock_available/models/product_product.py
@@ -21,8 +21,11 @@ class ProductProduct(models.Model):
 
         By default, available to promise = forecasted quantity.
 
-        Must be overridden by another module that actually implement
-        computations."""
+        **Each** sub-module **must** override this method in **both**
+            `product.product` **and** `product.template`, because we can't
+            decide in advance how to compute the template's quantity from the
+            variants.
+        """
         for prod in self:
             prod.immediately_usable_qty = prod.virtual_available
 
diff --git a/stock_available/models/product_template.py b/stock_available/models/product_template.py
index a7f1fcc4b..96db9b15f 100644
--- a/stock_available/models/product_template.py
+++ b/stock_available/models/product_template.py
@@ -12,12 +12,17 @@ class ProductTemplate(models.Model):
     @api.multi
     @api.depends('product_variant_ids.immediately_usable_qty')
     def _immediately_usable_qty(self):
-        """Compute the quantity using all the variants"""
+        """No-op implementation of the stock available to promise.
+
+        By default, available to promise = forecasted quantity.
+
+        **Each** sub-module **must** override this method in **both**
+            `product.product` **and** `product.template`, because we can't
+            decide in advance how to compute the template's quantity from the
+            variants.
+        """
         for tmpl in self:
-            tmpl.immediately_usable_qty = sum(
-                v.immediately_usable_qty
-                for v in tmpl.product_variant_ids
-            )
+            tmpl.immediately_usable_qty = tmpl.virtual_available
 
     immediately_usable_qty = fields.Float(
         digits=dp.get_precision('Product Unit of Measure'),