diff --git a/src/stores/CalendarStore.js b/src/stores/CalendarStore.js
index b4633c8..e12bc1d 100644
--- a/src/stores/CalendarStore.js
+++ b/src/stores/CalendarStore.js
@@ -1,10 +1,5 @@
 import { defineStore } from 'pinia'
-import {
-  toLocalString,
-  fromLocalString,
-  getLocaleFirstDay,
-  getLocaleWeekendDays,
-} from '@/utils/date'
+import { toLocalString, fromLocalString, getLocaleWeekendDays } from '@/utils/date'
 
 const MIN_YEAR = 1900
 const MAX_YEAR = 2100
@@ -19,7 +14,7 @@ export const useCalendarStore = defineStore('calendar', {
       select_days: 1000,
       min_year: MIN_YEAR,
       max_year: MAX_YEAR,
-      first_day: getLocaleFirstDay(),
+      first_day: 1, // Force Monday as week start
     },
   }),