diff --git a/dav_submission/views.py b/dav_submission/views.py
index 49f8de4..e6aeab9 100644
--- a/dav_submission/views.py
+++ b/dav_submission/views.py
@@ -153,10 +153,17 @@ class UploadView(generic.edit.FormView):
     def _sanitize_filename(self, input):
         max_length = None
         discard_chars = u''
+        replace_chars = {
+            u'ä': u'ae',
+            u'ö': u'oe',
+            u'ü': u'ue',
+            u'ß': u'ss',
+            u'Ä': u'Ae',
+            u'Ö': u'Oe',
+            u'Ü': u'Ue',
+        }
         allowed_chars = (u'abcdefghijklmnopqrstuvwxyz'
-                         u'äöüß'
                          u'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
-                         u'ÄÖÜ'
                          u'0123456789'
                          u'._-')
         non_allowed_substitute = u'_'
@@ -169,6 +176,8 @@ class UploadView(generic.edit.FormView):
         for c in input:
             if c in discard_chars:
                 continue
+            elif c in replace_chars:
+                r += replace_chars[c]
             elif allowed_chars is not None and c in allowed_chars:
                 r += c
             elif allowed_chars is None and c.isalnum():