diff --git a/src/calibre/utils/filenames.py b/src/calibre/utils/filenames.py
index 887bb0fa93..85d39a01e1 100644
--- a/src/calibre/utils/filenames.py
+++ b/src/calibre/utils/filenames.py
@@ -1,4 +1,4 @@
-from __future__ import unicode_literals
+from __future__ import absolute_import, division, print_function, unicode_literals
 '''
 Make strings safe for use as ASCII filenames, while trying to preserve as much
 meaning as possible.