diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 3783692b29b..b324b43177d 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -174,7 +174,7 @@ class SaleOrder(models.Model):
         return super(SaleOrder, self)._track_subtype(init_values)
 
     @api.multi
-    @api.onchange('partner_shipping_id')
+    @api.onchange('partner_shipping_id', 'partner_id')
     def onchange_partner_shipping_id(self):
         """
         Trigger the change of fiscal position when the shipping address is modified.
diff --git a/addons/sale/wizard/sale_make_invoice_advance.py b/addons/sale/wizard/sale_make_invoice_advance.py
index a543f598148..925877b75e7 100644
--- a/addons/sale/wizard/sale_make_invoice_advance.py
+++ b/addons/sale/wizard/sale_make_invoice_advance.py
@@ -65,9 +65,8 @@ class SaleAdvancePaymentInv(models.TransientModel):
         if self.product_id.id:
             account_id = self.product_id.property_account_income_id.id
         if not account_id:
-            prop = ir_property_obj.get('property_account_income_categ_id', 'product.category')
-            prop_id = prop and prop.id or False
-            account_id = order.fiscal_position_id.map_account(prop_id)
+            inc_acc = ir_property_obj.get('property_account_income_categ_id', 'product.category')
+            account_id = order.fiscal_position_id.map_account(inc_acc).id if inc_acc else False
         if not account_id:
             raise UserError(
                 _('There is no income account defined for this product: "%s". You may have to install a chart of account from Accounting app, settings menu.') % \