diff --git a/addons/purchase_stock/models/stock.py b/addons/purchase_stock/models/stock.py
index 89a43a7a2c000e6799957c2d35b120ff0cb075cd..acd14c4f402a35ef16b18347d728f2e79d353b7c 100644
--- a/addons/purchase_stock/models/stock.py
+++ b/addons/purchase_stock/models/stock.py
@@ -19,7 +19,7 @@ class StockMove(models.Model):
     purchase_line_id = fields.Many2one('purchase.order.line',
         '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)
+        'Created Purchase Order Line', ondelete='set null', readonly=True, copy=False, index=True)
 
     @api.model
     def _prepare_merge_moves_distinct_fields(self):