diff --git a/biscuit/apps/chronos/util.py b/biscuit/apps/chronos/util.py
index 1361b9db07fc8378508c2d16bbce3203c290d24d..6fcf478124eb7c243caec984fa9565a1f943e4fa 100644
--- a/biscuit/apps/chronos/util.py
+++ b/biscuit/apps/chronos/util.py
@@ -28,7 +28,7 @@ class CalendarWeek:
         if not self.year:
             self.year = today.year
         if not self.week:
-            self.week = today.isoweekday()
+            self.week = imt(today.strptime('%V'))
 
     def __str__(self) -> str:
         return '%s %d (%s %s %s)' % (_('Kalenderwoche'), self.week, self[0], _('to'), self[-1])