diff --git a/web/src/lib/openinghours.ts b/web/src/lib/openinghours.ts
index 390be21..c53b57e 100644
--- a/web/src/lib/openinghours.ts
+++ b/web/src/lib/openinghours.ts
@@ -1,6 +1,7 @@
 import {
   startOfToday,
   isAfter,
+  getISODay,
   parseISO,
   isSameDay,
   compareDesc,
@@ -199,7 +200,7 @@ export function getTodaysOpeningHoursForFunction(
   if (!week) {
     return "?";
   }
-  const weekdayIndex = startOfToday().getDay();
+  const weekdayIndex = getISODay(startOfToday()) - 1;
   const weekday = WEEKDAYS[weekdayIndex];
   const hours = week[weekday];
   if (hours.timeFrom && hours.timeTo) {