diff --git a/application/Calendar/CalendarModel.php b/application/Calendar/CalendarModel.php
index 3e247584e..efa2b8a39 100644
--- a/application/Calendar/CalendarModel.php
+++ b/application/Calendar/CalendarModel.php
@@ -75,9 +75,13 @@ class CalendarModel
     {
         $unicode_map = [
             '\u00f6' => 'ö',
+            'u00f6' => 'ö',
             '\u00fc' => 'ü',
+            'u00fc' => 'ü',
             '\u00e4' => 'ä',
+            'u00e4' => 'ä',
             '\u00df' => 'ß',
+            'u00df' => 'ß',
             '\u00e9' => 'é',
             '\u00e0' => 'à',
             '\u00f3' => 'ó',
@@ -544,7 +548,7 @@ WHERE `TimerecordingCategory`.`hourday`!='1' AND `TimerecordingCategory`.`hourda
                 'privateflag' => array('privateflag' => $data['private'], 'order' => $data['private']),
                 'isorganizer' => array('isorganizer' => $data['is_organizer']),
                 'attendees' => array('attendees' => json_encode($AttendeeArray)),
-                'organizer' => array('organizer' => $data['organizer']),
+                'organizer' => array('organizer' => self::replace_unicode_sequences($data['organizer'])),
                 'accepted' => array('accepted' => $data['accepted']),
                 'recurrence' => array('recurrence' => $recurrence),
                 'attachment' => array('attachment' => $attachment, 'order' => $attachment),