diff --git a/addons/purchase/models/stock.py b/addons/purchase/models/stock.py
index f02fddd8078..13517893217 100644
--- a/addons/purchase/models/stock.py
+++ b/addons/purchase/models/stock.py
@@ -16,7 +16,7 @@ class StockMove(models.Model):
     _inherit = 'stock.move'
 
     purchase_line_id = fields.Many2one('purchase.order.line',
-        'Purchase Order Line', ondelete='set null', index=True, readonly=True, copy=False)
+        'Purchase Order Line', ondelete='set null', index=True, readonly=True)
     created_purchase_line_id = fields.Many2one('purchase.order.line',
         'Created Purchase Order Line', ondelete='set null', readonly=True, copy=False)