diff --git a/calendar/js/app.js b/calendar/js/app.js
index 27b10721ed..dca128b23d 100644
--- a/calendar/js/app.js
+++ b/calendar/js/app.js
@@ -1004,14 +1004,15 @@ app.classes.calendar = AppJS.extend(
 	{
 		var content = this.et2.getArrayMgr('content').data;
 		var start_date = this.et2.getWidgetById('start').get_value();
-		var whole_day = this.et2.getWidgetById('whole_day').get_value();
+		var whole_day = this.et2.getWidgetById('whole_day');
+		var is_whole_day = whole_day && whole_day.get_value() == whole_day.options.selected_value;
 		var button = _button;
 		var that = this;
 		if (typeof content != 'undefined' && content.id != null &&
 			typeof content.recur_type != 'undefined' && content.recur_type != null && content.recur_type != 0
 		)
 		{
-			if (content.start != start_date || content.whole_day.toString() != whole_day)
+			if (content.start != start_date || content.whole_day != is_whole_day)
 			{
 				et2_dialog.show_dialog(function(_button_id)
 					{