diff --git a/account_chart_update/wizard/wizard_chart_update.py b/account_chart_update/wizard/wizard_chart_update.py
index 79efc3f29..f8c251ea5 100644
--- a/account_chart_update/wizard/wizard_chart_update.py
+++ b/account_chart_update/wizard/wizard_chart_update.py
@@ -332,6 +332,8 @@ class wizard_update_charts_accounts(orm.TransientModel):
         """
         Adds a tax template -> tax id to the mapping.
         """
+        if context is None:
+            context = {}
         if not tax_templ:
             return False
         if tax_templ_mapping.get(tax_templ.id):