diff --git a/core/models.py b/core/models.py
index f21b11f0..6bbc12d7 100644
--- a/core/models.py
+++ b/core/models.py
@@ -550,7 +550,10 @@ class Order(ExportModelOperationsMixin("order"), NiceModel):
     def total_quantity(self) -> int:
         return sum([op.quantity for op in self.order_products.all()])
 
-    def add_product(self, product_uuid: str | None = None, attributes: list = [], update_quantity: bool = True):
+    def add_product(self, product_uuid: str | None = None, attributes: list = None, update_quantity: bool = True):
+        if attributes is None:
+            attributes = []
+
         if self.status not in ["PENDING", "MOMENTAL"]:
             raise ValueError(_("you cannot add products to an order that is not a pending one"))
         try:
@@ -569,7 +572,7 @@ class Order(ExportModelOperationsMixin("order"), NiceModel):
             order_product, is_created = OrderProduct.objects.get_or_create(
                 product=product,
                 order=self,
-                attributes=json.dumps(attributes) if attributes else {},
+                attributes=json.dumps(attributes),
                 defaults={"quantity": 1, "buy_price": product.price},
             )
             if not is_created and update_quantity: