diff --git a/addons/mrp_repair/views/mrp_repair_views.xml b/addons/mrp_repair/views/mrp_repair_views.xml
index 275843dab6f..a1a0bf37ef1 100644
--- a/addons/mrp_repair/views/mrp_repair_views.xml
+++ b/addons/mrp_repair/views/mrp_repair_views.xml
@@ -59,7 +59,7 @@
                                 <field name="product_qty"/>
                                 <field name="product_uom" groups="product.group_uom"/>
                             </div>
-                            <field name="lot_id" domain="[('product_id', '=', product_id)]" context="{'default_product_id': product_id}" groups="stock.group_production_lot" attrs="{'required': [('tracking', '!=', 'none')]}"/>
+                            <field name="lot_id" domain="[('product_id', '=', product_id)]" context="{'default_product_id': product_id}" groups="stock.group_production_lot" attrs="{'required': [('tracking', '!=', 'none')], 'readonly': [('state', '=', 'done')]}"/>
                             <field name="partner_id" attrs="{'required':[('invoice_method','!=','none')]}"/>
                             <field name="address_id" groups="sale.group_delivery_invoice_address"/>
                         </group>