diff --git a/apps/dav/lib/CalDAV/CalendarObject.php b/apps/dav/lib/CalDAV/CalendarObject.php
index 949886bf32ab979e0042449768a86d0616db5c99..0db592898afdfa0c381c2662a353a09da77cb54e 100644
--- a/apps/dav/lib/CalDAV/CalendarObject.php
+++ b/apps/dav/lib/CalDAV/CalendarObject.php
@@ -32,6 +32,22 @@ use Sabre\VObject\Reader;
 
 class CalendarObject extends \Sabre\CalDAV\CalendarObject {
 
+	/**
+	 * CalendarObject constructor.
+	 *
+	 * @param CalDavBackend $caldavBackend
+	 * @param array $calendarInfo
+	 * @param array $objectData
+	 */
+	public function __construct(CalDavBackend $caldavBackend, array $calendarInfo,
+								array $objectData) {
+		parent::__construct($caldavBackend, $calendarInfo, $objectData);
+
+		if ($this->isShared()) {
+			unset($this->objectData['size']);
+		}
+	}
+
 	/**
 	 * @inheritdoc
 	 */