diff --git a/stdlib/winreg.pyi b/stdlib/winreg.pyi
index 5fff1104e..3ea47cb53 100644
--- a/stdlib/winreg.pyi
+++ b/stdlib/winreg.pyi
@@ -1,101 +1,101 @@
+import sys
 from _typeshed import Self
 from types import TracebackType
 from typing import Any, Type, Union
 from typing_extensions import final
 
-_KeyType = Union[HKEYType, int]
+if sys.platform == "win32":
+    _KeyType = Union[HKEYType, int]
+    def CloseKey(__hkey: _KeyType) -> None: ...
+    def ConnectRegistry(__computer_name: str | None, __key: _KeyType) -> HKEYType: ...
+    def CreateKey(__key: _KeyType, __sub_key: str | None) -> HKEYType: ...
+    def CreateKeyEx(key: _KeyType, sub_key: str | None, reserved: int = ..., access: int = ...) -> HKEYType: ...
+    def DeleteKey(__key: _KeyType, __sub_key: str) -> None: ...
+    def DeleteKeyEx(key: _KeyType, sub_key: str, access: int = ..., reserved: int = ...) -> None: ...
+    def DeleteValue(__key: _KeyType, __value: str) -> None: ...
+    def EnumKey(__key: _KeyType, __index: int) -> str: ...
+    def EnumValue(__key: _KeyType, __index: int) -> tuple[str, Any, int]: ...
+    def ExpandEnvironmentStrings(__str: str) -> str: ...
+    def FlushKey(__key: _KeyType) -> None: ...
+    def LoadKey(__key: _KeyType, __sub_key: str, __file_name: str) -> None: ...
+    def OpenKey(key: _KeyType, sub_key: str, reserved: int = ..., access: int = ...) -> HKEYType: ...
+    def OpenKeyEx(key: _KeyType, sub_key: str, reserved: int = ..., access: int = ...) -> HKEYType: ...
+    def QueryInfoKey(__key: _KeyType) -> tuple[int, int, int]: ...
+    def QueryValue(__key: _KeyType, __sub_key: str | None) -> str: ...
+    def QueryValueEx(__key: _KeyType, __name: str) -> tuple[Any, int]: ...
+    def SaveKey(__key: _KeyType, __file_name: str) -> None: ...
+    def SetValue(__key: _KeyType, __sub_key: str, __type: int, __value: str) -> None: ...
+    def SetValueEx(
+        __key: _KeyType, __value_name: str | None, __reserved: Any, __type: int, __value: str | int
+    ) -> None: ...  # reserved is ignored
+    def DisableReflectionKey(__key: _KeyType) -> None: ...
+    def EnableReflectionKey(__key: _KeyType) -> None: ...
+    def QueryReflectionKey(__key: _KeyType) -> bool: ...
+    HKEY_CLASSES_ROOT: int
+    HKEY_CURRENT_USER: int
+    HKEY_LOCAL_MACHINE: int
+    HKEY_USERS: int
+    HKEY_PERFORMANCE_DATA: int
+    HKEY_CURRENT_CONFIG: int
+    HKEY_DYN_DATA: int
 
-def CloseKey(__hkey: _KeyType) -> None: ...
-def ConnectRegistry(__computer_name: str | None, __key: _KeyType) -> HKEYType: ...
-def CreateKey(__key: _KeyType, __sub_key: str | None) -> HKEYType: ...
-def CreateKeyEx(key: _KeyType, sub_key: str | None, reserved: int = ..., access: int = ...) -> HKEYType: ...
-def DeleteKey(__key: _KeyType, __sub_key: str) -> None: ...
-def DeleteKeyEx(key: _KeyType, sub_key: str, access: int = ..., reserved: int = ...) -> None: ...
-def DeleteValue(__key: _KeyType, __value: str) -> None: ...
-def EnumKey(__key: _KeyType, __index: int) -> str: ...
-def EnumValue(__key: _KeyType, __index: int) -> tuple[str, Any, int]: ...
-def ExpandEnvironmentStrings(__str: str) -> str: ...
-def FlushKey(__key: _KeyType) -> None: ...
-def LoadKey(__key: _KeyType, __sub_key: str, __file_name: str) -> None: ...
-def OpenKey(key: _KeyType, sub_key: str, reserved: int = ..., access: int = ...) -> HKEYType: ...
-def OpenKeyEx(key: _KeyType, sub_key: str, reserved: int = ..., access: int = ...) -> HKEYType: ...
-def QueryInfoKey(__key: _KeyType) -> tuple[int, int, int]: ...
-def QueryValue(__key: _KeyType, __sub_key: str | None) -> str: ...
-def QueryValueEx(__key: _KeyType, __name: str) -> tuple[Any, int]: ...
-def SaveKey(__key: _KeyType, __file_name: str) -> None: ...
-def SetValue(__key: _KeyType, __sub_key: str, __type: int, __value: str) -> None: ...
-def SetValueEx(
-    __key: _KeyType, __value_name: str | None, __reserved: Any, __type: int, __value: str | int
-) -> None: ...  # reserved is ignored
-def DisableReflectionKey(__key: _KeyType) -> None: ...
-def EnableReflectionKey(__key: _KeyType) -> None: ...
-def QueryReflectionKey(__key: _KeyType) -> bool: ...
+    KEY_ALL_ACCESS: int
+    KEY_WRITE: int
+    KEY_READ: int
+    KEY_EXECUTE: int
+    KEY_QUERY_VALUE: int
+    KEY_SET_VALUE: int
+    KEY_CREATE_SUB_KEY: int
+    KEY_ENUMERATE_SUB_KEYS: int
+    KEY_NOTIFY: int
+    KEY_CREATE_LINK: int
 
-HKEY_CLASSES_ROOT: int
-HKEY_CURRENT_USER: int
-HKEY_LOCAL_MACHINE: int
-HKEY_USERS: int
-HKEY_PERFORMANCE_DATA: int
-HKEY_CURRENT_CONFIG: int
-HKEY_DYN_DATA: int
+    KEY_WOW64_64KEY: int
+    KEY_WOW64_32KEY: int
 
-KEY_ALL_ACCESS: int
-KEY_WRITE: int
-KEY_READ: int
-KEY_EXECUTE: int
-KEY_QUERY_VALUE: int
-KEY_SET_VALUE: int
-KEY_CREATE_SUB_KEY: int
-KEY_ENUMERATE_SUB_KEYS: int
-KEY_NOTIFY: int
-KEY_CREATE_LINK: int
+    REG_BINARY: int
+    REG_DWORD: int
+    REG_DWORD_LITTLE_ENDIAN: int
+    REG_DWORD_BIG_ENDIAN: int
+    REG_EXPAND_SZ: int
+    REG_LINK: int
+    REG_MULTI_SZ: int
+    REG_NONE: int
+    REG_QWORD: int
+    REG_QWORD_LITTLE_ENDIAN: int
+    REG_RESOURCE_LIST: int
+    REG_FULL_RESOURCE_DESCRIPTOR: int
+    REG_RESOURCE_REQUIREMENTS_LIST: int
+    REG_SZ: int
 
-KEY_WOW64_64KEY: int
-KEY_WOW64_32KEY: int
+    REG_CREATED_NEW_KEY: int  # undocumented
+    REG_LEGAL_CHANGE_FILTER: int  # undocumented
+    REG_LEGAL_OPTION: int  # undocumented
+    REG_NOTIFY_CHANGE_ATTRIBUTES: int  # undocumented
+    REG_NOTIFY_CHANGE_LAST_SET: int  # undocumented
+    REG_NOTIFY_CHANGE_NAME: int  # undocumented
+    REG_NOTIFY_CHANGE_SECURITY: int  # undocumented
+    REG_NO_LAZY_FLUSH: int  # undocumented
+    REG_OPENED_EXISTING_KEY: int  # undocumented
+    REG_OPTION_BACKUP_RESTORE: int  # undocumented
+    REG_OPTION_CREATE_LINK: int  # undocumented
+    REG_OPTION_NON_VOLATILE: int  # undocumented
+    REG_OPTION_OPEN_LINK: int  # undocumented
+    REG_OPTION_RESERVED: int  # undocumented
+    REG_OPTION_VOLATILE: int  # undocumented
+    REG_REFRESH_HIVE: int  # undocumented
+    REG_WHOLE_HIVE_VOLATILE: int  # undocumented
 
-REG_BINARY: int
-REG_DWORD: int
-REG_DWORD_LITTLE_ENDIAN: int
-REG_DWORD_BIG_ENDIAN: int
-REG_EXPAND_SZ: int
-REG_LINK: int
-REG_MULTI_SZ: int
-REG_NONE: int
-REG_QWORD: int
-REG_QWORD_LITTLE_ENDIAN: int
-REG_RESOURCE_LIST: int
-REG_FULL_RESOURCE_DESCRIPTOR: int
-REG_RESOURCE_REQUIREMENTS_LIST: int
-REG_SZ: int
+    error = OSError
 
-REG_CREATED_NEW_KEY: int  # undocumented
-REG_LEGAL_CHANGE_FILTER: int  # undocumented
-REG_LEGAL_OPTION: int  # undocumented
-REG_NOTIFY_CHANGE_ATTRIBUTES: int  # undocumented
-REG_NOTIFY_CHANGE_LAST_SET: int  # undocumented
-REG_NOTIFY_CHANGE_NAME: int  # undocumented
-REG_NOTIFY_CHANGE_SECURITY: int  # undocumented
-REG_NO_LAZY_FLUSH: int  # undocumented
-REG_OPENED_EXISTING_KEY: int  # undocumented
-REG_OPTION_BACKUP_RESTORE: int  # undocumented
-REG_OPTION_CREATE_LINK: int  # undocumented
-REG_OPTION_NON_VOLATILE: int  # undocumented
-REG_OPTION_OPEN_LINK: int  # undocumented
-REG_OPTION_RESERVED: int  # undocumented
-REG_OPTION_VOLATILE: int  # undocumented
-REG_REFRESH_HIVE: int  # undocumented
-REG_WHOLE_HIVE_VOLATILE: int  # undocumented
-
-error = OSError
-
-# Though this class has a __name__ of PyHKEY, it's exposed as HKEYType for some reason
-@final
-class HKEYType:
-    def __bool__(self) -> bool: ...
-    def __int__(self) -> int: ...
-    def __enter__(self: Self) -> Self: ...
-    def __exit__(
-        self, exc_type: Type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
-    ) -> bool | None: ...
-    def Close(self) -> None: ...
-    def Detach(self) -> int: ...
+    # Though this class has a __name__ of PyHKEY, it's exposed as HKEYType for some reason
+    @final
+    class HKEYType:
+        def __bool__(self) -> bool: ...
+        def __int__(self) -> int: ...
+        def __enter__(self: Self) -> Self: ...
+        def __exit__(
+            self, exc_type: Type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+        ) -> bool | None: ...
+        def Close(self) -> None: ...
+        def Detach(self) -> int: ...