diff --git a/stdlib/2and3/zlib.pyi b/stdlib/2and3/zlib.pyi
index 4ea537215..d6e07bbf8 100644
--- a/stdlib/2and3/zlib.pyi
+++ b/stdlib/2and3/zlib.pyi
@@ -38,8 +38,8 @@ class _Decompress:
     def copy(self) -> _Decompress: ...
 
 
-def adler32(data: bytes, value: int = ...) -> int: ...
-def compress(data: bytes, level: int = ...) -> bytes: ...
+def adler32(__data: bytes, __value: int = ...) -> int: ...
+def compress(__data: bytes, level: int = ...) -> bytes: ...
 if sys.version_info >= (3,):
     def compressobj(level: int = ..., method: int = ..., wbits: int = ...,
                     memLevel: int = ..., strategy: int = ...,
@@ -47,8 +47,8 @@ if sys.version_info >= (3,):
 else:
     def compressobj(level: int = ..., method: int = ..., wbits: int = ...,
                     memlevel: int = ..., strategy: int = ...) -> _Compress: ...
-def crc32(data: bytes, value: int = ...) -> int: ...
-def decompress(data: bytes, wbits: int = ..., bufsize: int = ...) -> bytes: ...
+def crc32(__data: bytes, __value: int = ...) -> int: ...
+def decompress(__data: bytes, wbits: int = ..., bufsize: int = ...) -> bytes: ...
 if sys.version_info >= (3,):
     def decompressobj(wbits: int = ..., zdict: bytes = ...) -> _Decompress: ...
 else: