diff --git a/win_toolchain/toolchain2013.py b/win_toolchain/toolchain2013.py
index 0cda59039..201e6c7b4 100755
--- a/win_toolchain/toolchain2013.py
+++ b/win_toolchain/toolchain2013.py
@@ -196,10 +196,11 @@ def DownloadSDK8():
       'Running sdksetup.exe to download Win8 SDK (may request elevation)...\n')
   count = 0
   while count < 5:
-    rc = os.system(target_path + ' /quiet '
-                   '/features OptionId.WindowsDesktopDebuggers '
-                             'OptionId.WindowsDesktopSoftwareDevelopmentKit '
-                   '/layout ' + standalone_path)
+    rc = subprocess.call([target_path,
+                          '/quiet',
+                          '/features', 'OptionId.WindowsDesktopDebuggers',
+                              'OptionId.WindowsDesktopSoftwareDevelopmentKit',
+                          '/layout', standalone_path])
     if rc == 0:
       return standalone_path
     count += 1