diff --git a/stock.py b/stock.py
index 6f3f586..8e99a6c 100644
--- a/stock.py
+++ b/stock.py
@@ -1,7 +1,7 @@
 # This file is part of stock_lot_csv module for Tryton.
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
-from StringIO import StringIO
+from io import StringIO
 from csv import reader
 from logging import getLogger
 from trytond.pool import Pool