diff --git a/Misc/NEWS.d/next/Build/2021-09-16-18-00-43.bpo-45220.TgbkvW.rst b/Misc/NEWS.d/next/Build/2021-09-16-18-00-43.bpo-45220.TgbkvW.rst
new file mode 100644
index 000000000000000..8bbd634fa61a37e
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-09-16-18-00-43.bpo-45220.TgbkvW.rst
@@ -0,0 +1,3 @@
+Avoid building with the Windows 11 SDK previews automatically. This may be
+overridden by setting the ``DefaultWindowsSDKVersion`` environment variable
+before building.
diff --git a/PCbuild/python.props b/PCbuild/python.props
index 295b7293f9d7bba..0d25e51126a714d 100644
--- a/PCbuild/python.props
+++ b/PCbuild/python.props
@@ -106,6 +106,9 @@
     <!-- Sometimes the version in the registry has to .0 suffix, and sometimes it doesn't. Check and add it -->
     <_RegistryVersion Condition="$(_RegistryVersion) != '' and !$(_RegistryVersion.EndsWith('.0'))">$(_RegistryVersion).0</_RegistryVersion>
 
+    <!-- Avoid upgrading to Windows 11 SDK for now, but assume the latest Win10 SDK is installed -->
+    <_RegistryVersion Condition="$([System.Version]::Parse($(_RegistryVersion))) >= $([System.Version]::Parse(`10.0.22000.0`))">10.0.19041.0</_RegistryVersion>
+
     <!-- The minimum allowed SDK version to use for building -->
     <DefaultWindowsSDKVersion>10.0.10586.0</DefaultWindowsSDKVersion>
     <DefaultWindowsSDKVersion Condition="$([System.Version]::Parse($(_RegistryVersion))) > $([System.Version]::Parse($(DefaultWindowsSDKVersion)))">$(_RegistryVersion)</DefaultWindowsSDKVersion>