diff --git a/account_financial_report/report/open_items.py b/account_financial_report/report/open_items.py
index f9f5143f..be0c21f9 100644
--- a/account_financial_report/report/open_items.py
+++ b/account_financial_report/report/open_items.py
@@ -2,6 +2,7 @@
 # Copyright 2020 ForgeFlow S.L. (https://www.forgeflow.com)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
+import operator
 from datetime import date, datetime
 
 from odoo import api, models