diff --git a/webapp/TargetedMS/js/scheduler.js b/webapp/TargetedMS/js/scheduler.js
index f289542e2..89b1109eb 100644
--- a/webapp/TargetedMS/js/scheduler.js
+++ b/webapp/TargetedMS/js/scheduler.js
@@ -385,6 +385,13 @@ $(function() {
     });
 
 
+    // Format to datetime-local's fixed 'yyyy-MM-ddTHH:mm' from local fields; DateFormat.format.date zeroes the time in timezones whose label contains a colon (e.g. Honolulu).
+    function toDateTimeLocalValue(date) {
+        let pad = function(n) { return (n < 10 ? '0' : '') + n; };
+        return date.getFullYear() + '-' + pad(date.getMonth() + 1) + '-' + pad(date.getDate())
+            + 'T' + pad(date.getHours()) + ':' + pad(date.getMinutes());
+    }
+
     function editEvent(event) {
         let startDate = event.startDate;
         let endDate = event.endDate;
@@ -396,8 +403,8 @@ $(function() {
             endDate.setDate(endDate.getDate() - 1);
         }
 
-        let startDateFormatted = DateFormat.format.date(startDate, LABKEY.container.formats.dateTimeFormat);
-        let endDateFormatted = DateFormat.format.date(endDate, LABKEY.container.formats.dateTimeFormat);
+        let startDateFormatted = toDateTimeLocalValue(startDate);
+        let endDateFormatted = toDateTimeLocalValue(endDate);
 
         // remove the old event log rows
         removeEventLog();