diff --git a/pykolab/xml/todo.py b/pykolab/xml/todo.py
--- a/pykolab/xml/todo.py
+++ b/pykolab/xml/todo.py
@@ -38,6 +38,9 @@
 class Todo(Event):
     type = 'task'
 
+    # This have to be a copy (see T1221)
+    properties_map = Event.properties_map.copy()
+
     def __init__(self, from_ical="", from_string=""):
         self._attendees = []
         self._categories = []
diff --git a/tests/unit/test-003-event.py b/tests/unit/test-003-event.py
--- a/tests/unit/test-003-event.py
+++ b/tests/unit/test-003-event.py
@@ -889,7 +889,7 @@
 
         self.assertIsInstance(data, dict)
         self.assertIsInstance(data['start'], datetime.datetime)
-        # self.assertIsInstance(data['end'], datetime.datetime)
+        self.assertIsInstance(data['end'], datetime.datetime)
         self.assertIsInstance(data['created'], datetime.datetime)
         self.assertIsInstance(data['lastmodified-date'], datetime.datetime)
         self.assertEqual(data['uid'], '75c740bb-b3c6-442c-8021-ecbaeb0a025e')
@@ -936,7 +936,7 @@
         e2.set_lastmodified()
 
         diff = compute_diff(e1.to_dict(), e2.to_dict(), True)
-        self.assertEqual(len(diff), 4, "Diff: (length: %d):\r\n%r\r\n%r" % (len(diff), diff, e2.__str__()))
+        self.assertEqual(len(diff), 5, "Diff: (length: %d):\r\n%r\r\n%r" % (len(diff), diff, e2.__str__()))
 
         ps = self._find_prop_in_list(diff, 'summary')
         self.assertIsInstance(ps, OrderedDict)
diff --git a/tests/unit/test-017-diff.py b/tests/unit/test-017-diff.py
--- a/tests/unit/test-017-diff.py
+++ b/tests/unit/test-017-diff.py
@@ -190,18 +190,19 @@
         self.assertEqual(diff[0]['old'], 0)
         self.assertEqual(diff[0]['new'], 1)
 
-        self.assertEqual(diff[1]['property'], 'description')
-        self.assertEqual(diff[1]['old'], '')
+        self.assertEqual(diff[1]['property'], 'summary')
+        self.assertEqual(diff[1]['old'], 'Old attachments')
+        self.assertEqual(diff[1]['new'], 'New attachments')
 
-        self.assertEqual(diff[2]['property'], 'summary')
-        self.assertEqual(diff[2]['old'], 'Old attachments')
-        self.assertEqual(diff[2]['new'], 'New attachments')
+        self.assertEqual(diff[2]['property'], 'attach')
+        self.assertEqual(diff[2]['new'], None)
+        self.assertEqual(diff[2]['old']['uri'], "cid:silhouette.1427297477.7514.png")
 
-        self.assertEqual(diff[3]['property'], 'attach')
-        self.assertEqual(diff[3]['new'], None)
-        self.assertEqual(diff[3]['old']['uri'], "cid:silhouette.1427297477.7514.png")
+        self.assertEqual(diff[3]['property'], 'lastmodified-date')
+
+        self.assertEqual(diff[4]['property'], 'description')
+        self.assertEqual(diff[4]['old'], '')
 
-        self.assertEqual(diff[4]['property'], 'lastmodified-date')
 
 if __name__ == '__main__':
     unittest.main()