diff --git a/odex25_mobile/odex_mobile/models/hr_firebase_notification.py b/odex25_mobile/odex_mobile/models/hr_firebase_notification.py
index 507d1e9b2..be8bf0984 100644
--- a/odex25_mobile/odex_mobile/models/hr_firebase_notification.py
+++ b/odex25_mobile/odex_mobile/models/hr_firebase_notification.py
@@ -184,7 +184,7 @@ class HrPersonalPermission(models.Model):
 
             _logger.warning("Write inner")
             user = self.employee_id.user_id
-            timezone = user.tz or 'GMT'
+            timezone = user.tz or 'UTC'
             local_tz = pytz.timezone(timezone)
             date_from_local = self.date_from.astimezone(local_tz) if self.date_from else None
             date_to_local = self.date_to.astimezone(local_tz) if self.date_to else None