diff --git a/3rdparty/fullcalendar/js/fullcalendar.js b/3rdparty/fullcalendar/js/fullcalendar.js
index 314f8c8a1a5..bd5938cd002 100644
--- a/3rdparty/fullcalendar/js/fullcalendar.js
+++ b/3rdparty/fullcalendar/js/fullcalendar.js
@@ -4662,7 +4662,7 @@ function DayEventRenderer() {
 					"</span>";
 			}
 			html +=
-				"<span class='fc-event-title'>" + event.title + "</span>" +
+				"<span class='fc-event-title'>" + htmlEscape(event.title) + "</span>" +
 				"</div>";
 			if (seg.isEnd && isEventResizable(event)) {
 				html +=
@@ -5220,5 +5220,5 @@ function HorizontalPositionCache(getElement) {
 	};
 	
 }
-
+
 })(jQuery);