diff -r 7629902e7554 -r 8e46ed1a0b8a server/sources/storages.py
--- a/server/sources/storages.py	Fri Sep 11 15:29:25 2015 +0200
+++ b/server/sources/storages.py	Fri Sep 11 15:50:29 2015 +0200
@@ -105,7 +105,7 @@
 
 class BytesFileSystemStorage(Storage):
     """store Bytes attribute value on the file system"""
-    def __init__(self, defaultdir, fsencoding='utf-8', wmode=0444):
+    def __init__(self, defaultdir, fsencoding='utf-8', wmode=0o444):
         if type(defaultdir) is unicode:
             defaultdir = defaultdir.encode(fsencoding)
         self.default_directory = defaultdir