diff --git a/services/univention-ad-connector/ad-connector.py b/services/univention-ad-connector/ad-connector.py
index d97a884..c768cc9 100644
--- a/services/univention-ad-connector/ad-connector.py
+++ b/services/univention-ad-connector/ad-connector.py
@@ -32,7 +32,11 @@
 # <http://www.gnu.org/licenses/>.
 
 __package__='' 	# workaround for PEP 366
-import listener, cPickle, time, os
+import listener
+import cPickle
+import time
+import os
+import shutil
 import univention.debug
 
 name='ad-connector'
@@ -87,29 +91,31 @@ def _dump_changes_to_file_and_check_file(directory, dn, new, old, old_dn):
 
 	ob=(dn, new, old, old_dn)
 
-	filename=os.path.join(directory,"%f"%time.time())
+	tmpdir = os.path.join(directory, 'tmp')
+	filename = "%f" % time.time()
+	filepath = os.path.join(tmpdir, filename)
 
-	_dump_object_to_file(filename, ob)
+	_dump_object_to_file(filepath, ob)
 
 	tmp_array = []
-	f=open(filename, 'r')
-	tmp_array = cPickle.load(f)
-	f.close()
+	with open(filepath, 'r') as fd:
+		tmp_array = cPickle.load(fd)
 
 	tmp_array_len = len(tmp_array)
 	if tmp_array_len != 4:
 		univention.debug.debug(univention.debug.LDAP, univention.debug.WARN, 'replacing broken cPickle in %s (len=%s) with plain pickle' % (filename, tmp_array_len))
-		_dump_object_to_file(filename, ob)
+		_dump_object_to_file(filepath, ob)
 
 		tmp_array = []
-		f=open(filename, 'r')
-		tmp_array = cPickle.load(f)
-		f.close()
+		with open(filepath, 'r') as fd:
+			tmp_array = cPickle.load(fd)
 
 		tmp_array_len = len(tmp_array)
 		if tmp_array_len != 4:
 			univention.debug.debug(univention.debug.LDAP, univention.debug.ERROR, 'pickle in %s (len=%s) seems to be broken' % (filename, tmp_array_len))
 
+	shutil.move(filepath, os.path.join(directory, filename))
+
 def handler(dn, new, old, command):
 
 	global group_objects