issue-21.diff

diff --git a/radicale/storage/filesystem.py b/radicale/storage/filesystem.py
index deeba20..32a26a7 100644
--- a/radicale/storage/filesystem.py
+++ b/radicale/storage/filesystem.py
@@ -28,6 +28,7 @@ import json
 import time
 import sys
 from contextlib import contextmanager
+from atomicwrites import AtomicWriter
 
 from .. import config, ical, log, pathutils
 
@@ -42,6 +43,14 @@ except:
     GIT_REPOSITORY = None
 
 
+class _EncodedAtomicWriter(AtomicWriter):
+    def __init__(self, path, encoding, mode="w", overwrite=True):
+        self._encoding = encoding
+        super().__init__(path, mode, overwrite)
+
+    def get_fileobject(self, **kwargs):
+        return super().get_fileobject(encoding=self._encoding, **kwargs)
+
 # This function overrides the builtin ``open`` function for this module
 # pylint: disable=W0622
 @contextmanager
@@ -49,8 +58,12 @@ def open(path, mode="r"):
     """Open a file at ``path`` with encoding set in the configuration."""
     # On enter
     abs_path = os.path.join(FOLDER, path.replace("/", os.sep))
-    with codecs.open(abs_path, mode, config.get("encoding", "stock")) as fd:
-        yield fd
+    if mode == "w":
+        with _EncodedAtomicWriter(abs_path, config.get("encoding", "stock"), mode).open() as fd:
+            yield fd
+    else:
+        with codecs.open(abs_path, mode, config.get("encoding", "stock")) as fd:
+            yield fd
     # On exit
     if GIT_REPOSITORY and mode == "w":
         path = os.path.relpath(abs_path, FOLDER)
@@ -60,7 +73,6 @@ def open(path, mode="r"):
             path.encode("utf-8"), committer=committer.encode("utf-8"))
 # pylint: enable=W0622
 
-
 class Collection(ical.Collection):
     """Collection stored in a flat ical file."""
     @property