diff --git a/src/pretix/static/pretixpresale/js/ui/main.js b/src/pretix/static/pretixpresale/js/ui/main.js
index 30bcc42d9..d1867bfe1 100644
--- a/src/pretix/static/pretixpresale/js/ui/main.js
+++ b/src/pretix/static/pretixpresale/js/ui/main.js
@@ -60,6 +60,7 @@ var form_handlers = function (el) {
             locale: $("body").attr("data-datetimelocale"),
             useCurrent: false,
             showClear: !$(this).prop("required"),
+            keepInvalid: true,
             icons: {
                 time: 'fa fa-clock-o',
                 date: 'fa fa-calendar',