diff --git a/resources/kolab/pimkolab/autotests/testutils.h b/resources/kolab/pimkolab/autotests/testutils.h
--- a/resources/kolab/pimkolab/autotests/testutils.h
+++ b/resources/kolab/pimkolab/autotests/testutils.h
@@ -136,7 +136,7 @@
     //TODO make sure that the UID does really not need to be persistent
     auto attendees = incidence->attendees();
     for (auto &attendee : attendees) {
-        attendee->setUid(QString());
+        attendee->setUid(attendee->email());
     }
     incidence->setAttendees(attendees);