diff --git a/calendar/js/et2_widget_event.js b/calendar/js/et2_widget_event.js
index 80dc988f79..277282ccc7 100644
--- a/calendar/js/et2_widget_event.js
+++ b/calendar/js/et2_widget_event.js
@@ -411,7 +411,7 @@ var et2_calendar_event = (function(){ "use strict"; return et2_valueWidget.exten
 		else if (this.getParent() && this.getParent().instanceOf(et2_calendar_planner_row))
 		{
 			// Less than 8 hours is small
-			this.div.toggleClass('calendar_calEventSmall',this.options.value.end_m - this.options.value.start_m < 480);
+			this.div.toggleClass('calendar_calEventSmall',this.options.value.end.valueOf() - this.options.value.start.valueOf() < 28800000);
 		}