diff --git a/creme/billing/views/export.py b/creme/billing/views/export.py
index 22df211908..8745f4e02e 100644
--- a/creme/billing/views/export.py
+++ b/creme/billing/views/export.py
@@ -1,6 +1,6 @@
 ################################################################################
 #    Creme is a free/open-source Customer Relationship Management software
-#    Copyright (C) 2009-2021  Hybird
+#    Copyright (C) 2009-2025  Hybird
 #
 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU Affero General Public License as published by
@@ -107,6 +107,6 @@ def get(self, request, *args, **kwargs):
         if isinstance(export_result, HttpResponse):
             return export_result
 
-        assert export_result, FileRef
+        assert isinstance(export_result, FileRef)
 
         return HttpResponseRedirect(export_result.get_download_absolute_url())