diff --git a/core/admin/mailu/internal/views/auth.py b/core/admin/mailu/internal/views/auth.py
index cea90e6d..6d37d923 100644
--- a/core/admin/mailu/internal/views/auth.py
+++ b/core/admin/mailu/internal/views/auth.py
@@ -28,7 +28,7 @@ def nginx_authentication():
         response = flask.Response()
         response.headers['Auth-Status'] = status
         response.headers['Auth-Error-Code'] = code
-        if int(flask.request.headers['Auth-Login-Attempt']) < 10:
+        if int(flask.request.headers('Auth-Login-Attempt',0)) < 10:
             response.headers['Auth-Wait'] = '3'
         return response
     raw_password = urllib.parse.unquote(headers['Auth-Pass']) if 'Auth-Pass' in headers else ''