diff --git a/l10n_it_delivery_note_order_link/models/sale_order.py b/l10n_it_delivery_note_order_link/models/sale_order.py
index 11a22822d774..3b36548625b0 100644
--- a/l10n_it_delivery_note_order_link/models/sale_order.py
+++ b/l10n_it_delivery_note_order_link/models/sale_order.py
@@ -14,9 +14,7 @@ class SaleOrder(models.Model):
 
     def _compute_delivery_notes(self):
         for order in self:
-            delivery_notes = order.order_line.mapped(
-                "delivery_note_line_ids.delivery_note_id"
-            )
+            delivery_notes = order.picking_ids.mapped("delivery_note_id")
 
             order.delivery_note_ids = delivery_notes
             order.delivery_note_count = len(delivery_notes)