diff --git a/stdlib/platform.pyi b/stdlib/platform.pyi
index 217882224d74..5617774b88f5 100644
--- a/stdlib/platform.pyi
+++ b/stdlib/platform.pyi
@@ -1,4 +1,5 @@
 import sys
+from typing_extensions import Literal
 
 if sys.version_info < (3, 8):
     import os
@@ -49,8 +50,19 @@ class uname_result(NamedTuple):
     machine: str
     processor: str
 
+if sys.platform == "win32":
+    def system() -> Literal["Windows"]: ...
+
+elif sys.platform == "linux":
+    def system() -> Literal["Linux"]: ...
+
+elif sys.platform == "darwin":
+    def system() -> Literal["Darwin"]: ...
+
+else:
+    def system() -> str: ...
+
 def uname() -> uname_result: ...
-def system() -> str: ...
 def node() -> str: ...
 def release() -> str: ...
 def version() -> str: ...