diff --git a/src/assets/js/backend_calendar_unavailabilities_modal.js b/src/assets/js/backend_calendar_unavailabilities_modal.js
index 127caf3c..681c8868 100644
--- a/src/assets/js/backend_calendar_unavailabilities_modal.js
+++ b/src/assets/js/backend_calendar_unavailabilities_modal.js
@@ -30,8 +30,8 @@ window.BackendCalendarUnavailabilitiesModal = window.BackendCalendarUnavailabili
          */
         $('#manage-unavailable #save-unavailable').click(function() {
             var $dialog = $('#manage-unavailable');
-            var start = Date.parse($dialog.find('#unavailable-start').val());
-            var end = Date.parse($dialog.find('#unavailable-end').val());
+            var start = $dialog.find('#unavailable-start').datetimepicker('getDate');
+            var end = Date.parse($dialog.find('#unavailable-end').datetimepicker('getDate'));
 
             if (start > end) {
                 // Start time is after end time - display message to user.