diff --git a/build/service/CalendarExtractor.php b/build/service/CalendarExtractor.php
index ff016da..ad206a2 100644
--- a/build/service/CalendarExtractor.php
+++ b/build/service/CalendarExtractor.php
@@ -286,6 +286,8 @@
 				---------------------------------------------------------*/
 				foreach($events as $start_t=>$stop_t){
 					$RAW .= "BEGIN:VEVENT\n";
+					$RAW .= "UID:$start_t\n";     // required
+					$RAW .= "DTSTAMP:$start_t\n"; // required
 					$RAW .= "DTSTART:$start_t\n";
 					$RAW .= "DTEND:$stop_t\n";
 					$RAW .= "SUMMARY:$type\n";