diff --git a/koha-tmpl/intranet-tmpl/prog/en/includes/js-date-format.inc b/koha-tmpl/intranet-tmpl/prog/en/includes/js-date-format.inc
index b9ef294f96..bce0620c48 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/includes/js-date-format.inc
+++ b/koha-tmpl/intranet-tmpl/prog/en/includes/js-date-format.inc
@@ -91,7 +91,7 @@
 
         window.$date_to_rfc3339 = function(value, options) {
             var dateformat = (options&&options.dateformat)||def_date_format;
-            let m = dayjs(value, get_date_pattern(dateformat));
+            let m = dayjs(value, get_date_pattern(dateformat), true);
             return m.format("YYYY-MM-DD");
         }