diff --git a/addons/hr_expense/hr_expense_demo.xml b/addons/hr_expense/hr_expense_demo.xml
index eddaf03ad38..b7b6cd37956 100644
--- a/addons/hr_expense/hr_expense_demo.xml
+++ b/addons/hr_expense/hr_expense_demo.xml
@@ -20,6 +20,7 @@
 
         <record id="air_ticket" model="product.product">
             <field name="list_price">700.0</field>
+            <field name="standard_price">700.0</field>
             <field name="type">service</field>
             <field name="name">Air Ticket</field>
             <field name="default_code">AT</field>
diff --git a/addons/purchase/purchase_view.xml b/addons/purchase/purchase_view.xml
index 15a9de84f43..d78fabcbb15 100644
--- a/addons/purchase/purchase_view.xml
+++ b/addons/purchase/purchase_view.xml
@@ -242,7 +242,7 @@
                                     <field name="invoice_method"/>
                                     <field name="invoiced"/>
                                     <field name="payment_term_id" widget="selection"/>
-                                    <field name="fiscal_position"/>
+                                    <field name="fiscal_position" attrs="{'readonly': [('invoiced','=', True)]}" />
                                     <!-- We do not need these fields anymore, the information is in open chatter -->
                                     <field name="validator" groups="base.group_no_one"/>
                                     <field name="date_approve" groups="base.group_no_one"/>