diff --git a/stdlib/3/platform.pyi b/stdlib/3/platform.pyi
index debf8d713..c854930cd 100644
--- a/stdlib/3/platform.pyi
+++ b/stdlib/3/platform.pyi
@@ -1,12 +1,16 @@
 # Stubs for platform (Python 3.5)
 
 from os import devnull as DEV_NULL
-from typing import Tuple, NamedTuple
+from typing import Optional, Tuple, NamedTuple
 import sys
 
-def libc_ver(executable: str = ..., lib: str = ..., version: str = ..., chunksize: int = ...) -> Tuple[str, str]: ...
-def linux_distribution(distname: str = ..., version: str = ..., id: str = ..., supported_dists: Tuple[str, ...] = ..., full_distribution_name: bool = ...) -> Tuple[str, str, str]: ...
-def dist(distname: str = ..., version: str = ..., id: str = ..., supported_dists: Tuple[str, ...] = ...) -> Tuple[str, str, str]: ...
+if sys.version_info >= (3, 8):
+    def libc_ver(executable: Optional[str] = ..., lib: str = ..., version: str = ..., chunksize: int = ...) -> Tuple[str, str]: ...
+else:
+    def libc_ver(executable: str = ..., lib: str = ..., version: str = ..., chunksize: int = ...) -> Tuple[str, str]: ...
+if sys.version_info < (3, 8):
+    def linux_distribution(distname: str = ..., version: str = ..., id: str = ..., supported_dists: Tuple[str, ...] = ..., full_distribution_name: bool = ...) -> Tuple[str, str, str]: ...
+    def dist(distname: str = ..., version: str = ..., id: str = ..., supported_dists: Tuple[str, ...] = ...) -> Tuple[str, str, str]: ...
 def win32_ver(release: str = ..., version: str = ..., csd: str = ..., ptype: str = ...) -> Tuple[str, str, str, str]: ...
 if sys.version_info >= (3, 8):
     def win32_edition() -> str: ...