diff --git a/purchase.py b/purchase.py
index 14cd897e57..c54eb5e33c 100644
--- a/purchase.py
+++ b/purchase.py
@@ -1,5 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
+from decimal import Decimal
+
 from trytond import backend
 from trytond.model import ModelSQL, ValueMixin, fields
 from trytond.pyson import Eval
@@ -187,9 +189,15 @@ class PurchaseLine:
         return result
 
     def get_move(self, move_type):
+        pool = Pool()
+        Currency = pool.get('currency.currency')
         move = super(PurchaseLine, self).get_move(move_type)
         if move and self.purchase.customer:
-            move.cost_price = move.unit_price
+            digits = move.__class__.cost_price.digits
+            cost_price = Currency.compute(
+                move.currency, move.unit_price, move.company.currency)
+            move.cost_price = cost_price.quantize(
+                Decimal(str(10.0 ** -digits[1])))
         return move
 
 
diff --git a/tests/scenario_sale_supply_drop_shipment.rst b/tests/scenario_sale_supply_drop_shipment.rst
index f44483fca9..50dd5b6beb 100644
--- a/tests/scenario_sale_supply_drop_shipment.rst
+++ b/tests/scenario_sale_supply_drop_shipment.rst
@@ -180,6 +180,8 @@ Receiving only 100 products::
     >>> move.quantity = 100
     >>> move.unit_price
     Decimal('3.0000')
+    >>> move.cost_price
+    Decimal('3.0000')
     >>> shipment.click('ship')
     >>> move, = shipment.customer_moves
     >>> move.unit_price