diff --git a/sale_order_blanket_order/models/sale_order.py b/sale_order_blanket_order/models/sale_order.py
index 5d4e8d84239..d11bbde786c 100644
--- a/sale_order_blanket_order/models/sale_order.py
+++ b/sale_order_blanket_order/models/sale_order.py
@@ -29,6 +29,7 @@ class SaleOrder(models.Model):
         required=True,
         help="Specifies the type of sale order: Normal, Blanket, or Call-off.",
         states=READONLY_FIELD_STATES,
+        index=True,
     )
     blanket_order_id = fields.Many2one(
         "sale.order",