1 files changed, 2 insertions, 2 deletions
diff --git a/www/js/utils.js b/www/js/utils.js
index 1359b39..fab6736 100644
--- a/www/js/utils.js
+++ b/www/js/utils.js
@@ -57,10 +57,10 @@ var weekday_short = new Array('So', 'Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa');
 
 function format_datetime(d) {
   if(Object.prototype.toString.call(d) !== '[object Date]') {
-    return d;
+    return '-';
   }
   if (d.toString() === 'Invalid Date') {
-    return d;
+    return '-';
   }
   var datetimestr = weekday_short[d.getDay()];
   datetimestr += ' ' + Number(d.getDate()).pad(2);