diff --git a/addons/sale_mrp/sale_mrp.py b/addons/sale_mrp/sale_mrp.py
index c168e0e1770..da0bd383187 100644
--- a/addons/sale_mrp/sale_mrp.py
+++ b/addons/sale_mrp/sale_mrp.py
@@ -141,7 +141,7 @@ class AccountInvoiceLine(models.Model):
                         prod_moves = [m for m in moves if m.product_id.id == product_id]
                         prod_qty_done = factor * qty_done
                         prod_quantity = factor * quantity
-                        average_price_unit += factor * self._compute_average_price(prod_qty_done, prod_quantity, prod_moves)
+                        average_price_unit += self._compute_average_price(prod_qty_done, prod_quantity, prod_moves)
                     price_unit = average_price_unit or price_unit
                     price_unit = uom_obj._compute_qty_obj(self.uom_id, price_unit, self.product_id.uom_id, round=False)
         return price_unit