diff --git a/subscription_oca/models/sale_subscription_line.py b/subscription_oca/models/sale_subscription_line.py
index a780e4075b..c7e407d5c1 100644
--- a/subscription_oca/models/sale_subscription_line.py
+++ b/subscription_oca/models/sale_subscription_line.py
@@ -146,6 +146,9 @@ def _compute_price_unit(self):
     )
     def _compute_discount(self):
         for record in self:
+            # Skip recomputation for existing lines that already have a discount
+            if record.id and record.discount:
+                continue
             if not (
                 record.product_id
                 and record.product_id.uom_id