diff --git a/calendar/inc/class.uiforms.inc.php b/calendar/inc/class.uiforms.inc.php
index bc2e61b904..ba0efbc326 100644
--- a/calendar/inc/class.uiforms.inc.php
+++ b/calendar/inc/class.uiforms.inc.php
@@ -202,6 +202,7 @@ class uiforms extends uical
 		$event = $content;
 		unset($event['new_alarm']);
 		unset($event['alarm']['delete_alarm']);
+		unset($event['duration']);
 
 		if (in_array($button,array('ignore','freetime','reedit')))	// called from conflict display
 		{