diff --git a/addons/hr_timesheet/hr_timesheet_view.xml b/addons/hr_timesheet/hr_timesheet_view.xml
index c9f7214ecca..e6769788cbb 100644
--- a/addons/hr_timesheet/hr_timesheet_view.xml
+++ b/addons/hr_timesheet/hr_timesheet_view.xml
@@ -12,7 +12,7 @@
                     <field domain="[('type','=','normal'),('state', '&lt;&gt;', 'close')]" name="account_id"/>
                     <field name="name"/>
                     <field name="unit_amount" on_change="on_change_unit_amount(product_id, unit_amount, product_uom_id)" sum="Total time"/>
-                    <field name="product_id" required="1" domain="[('type','=','service')]"/>
+                    <field name="product_id" on_change="on_change_unit_amount(product_id, unit_amount, product_uom_id)" required="1" domain="[('type','=','service')]"/>
                     <field name="product_uom_id" on_change="on_change_unit_amount(product_id, unit_amount, product_uom_id)"/>
                     <field name="amount" sum="Total cost"/>
                     <field name="general_account_id"/>