From e1c0eb03bea1222f46044d8ef95d7f18b2768237 Mon Sep 17 00:00:00 2001
From: Kevin Tong <yuto@microsoft.com>
Date: Wed, 6 Aug 2025 13:35:32 -0700
Subject: [PATCH] Update application.py

---
 msal/application.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/msal/application.py b/msal/application.py
index c58678ca..8cb5df19 100644
--- a/msal/application.py
+++ b/msal/application.py
@@ -2,6 +2,7 @@
 import json
 import time
 import logging
+import platform
 import sys
 import warnings
 from threading import Lock
@@ -789,7 +790,7 @@ def _build_client(self, client_credential, authority, skip_regional_client=False
         client_assertion_type = None
         default_headers = {
             "x-client-sku": SKU, "x-client-ver": __version__,
-            "x-client-os": sys.platform,
+            "x-client-os": platform.system(),
             "x-ms-lib-capability": "retry-after, h429",
         }
         if self.app_name: