diff --git a/app/routes/book-event.tsx b/app/routes/book-event.tsx
index 33eafa9..8dc8c06 100644
--- a/app/routes/book-event.tsx
+++ b/app/routes/book-event.tsx
@@ -52,7 +52,7 @@ export default function () {
       `${currentYear}-${currentMonth.toString().padStart(2, "0")}-01`,
     );
     setDatePickerMax(
-      `${currentYear}-${currentMonth.toString().padStart(2, "0")}-${currentDate.getUTCDate().toString().padStart(2, "0")}`,
+      `${currentYear}-${currentMonth.toString().padStart(2, "0")}-${new Date(currentYear, currentMonth, 0).getUTCDate()}`,
     );
   }, []);