diff --git a/models/stock_inventory_backdate.py b/models/stock_inventory_backdate.py
index b220277..2dabf76 100644
--- a/models/stock_inventory_backdate.py
+++ b/models/stock_inventory_backdate.py
@@ -293,10 +293,10 @@ class StockInventoryBackdate(models.Model):
 class StockInventoryBackdateLine(models.Model):
     _name = 'stock.inventory.backdate.line'
     _description = 'Backdated Inventory Adjustment Line'
-    _sql_constraints = [
-        ('unique_product_per_inventory', 'unique(inventory_id, product_id, lot_id, package_id, owner_id)',
-         'You cannot have duplicate products with the same lot/package/owner in the same adjustment!')
-    ]
+    _unique_product_per_inventory = models.Constraint(
+        'unique(inventory_id, product_id, lot_id, package_id, owner_id)',
+        'You cannot have duplicate products with the same lot/package/owner in the same adjustment!',
+    )
 
     inventory_id = fields.Many2one(
         'stock.inventory.backdate',