diff --git a/models/sale_order.py b/models/sale_order.py
index 37dbf78e578c1fe5092f14970e1f07ffd393baba..2ebe2fc9f03fd5f3c47e217a0a04afcf6e6543da 100644
--- a/models/sale_order.py
+++ b/models/sale_order.py
@@ -27,16 +27,17 @@ class SaleOrder(models.Model):
     # Business method
     # ------------------------------------------------------
     def clean_sale_order(self):
-        current_inter = list()
+        inter_list = list()
         for project in self.sale_project_ids:
             for inter in project.intervention_ids:
-                current_inter.append(
+                inter_list.append(
                     (project.id, inter.intervention_type_id.product_variant_id.id)
                 )
         for sol in self.order_line:
             if (
-                sol.product_id
-                and (sol.sale_project_id.id, sol.product_id.id) not in current_inter
+                sol.sale_project_id
+                and sol.product_id
+                and (sol.sale_project_id.id, sol.product_id.id) not in inter_list
             ):
                 sol.unlink()