diff --git a/stdlib/hmac.pyi b/stdlib/hmac.pyi
index af69fc7ea46d..c5ab94c6ca4b 100644
--- a/stdlib/hmac.pyi
+++ b/stdlib/hmac.pyi
@@ -1,5 +1,5 @@
 import sys
-from _typeshed import ReadableBuffer
+from _typeshed import ReadableBuffer, _BufferWithLen
 from collections.abc import Callable
 from types import ModuleType
 from typing import Any, AnyStr, overload
@@ -18,9 +18,9 @@ if sys.version_info >= (3, 8):
     # In reality digestmod has a default value, but the function always throws an error
     # if the argument is not given, so we pretend it is a required argument.
     @overload
-    def new(key: bytes, msg: ReadableBuffer | None, digestmod: _DigestMod) -> HMAC: ...
+    def new(key: bytes | bytearray, msg: ReadableBuffer | None, digestmod: _DigestMod) -> HMAC: ...
     @overload
-    def new(key: bytes, *, digestmod: _DigestMod) -> HMAC: ...
+    def new(key: bytes | bytearray, *, digestmod: _DigestMod) -> HMAC: ...
 
 else:
     def new(key: bytes, msg: ReadableBuffer | None = ..., digestmod: _DigestMod | None = ...) -> HMAC: ...
@@ -30,7 +30,7 @@ class HMAC:
     block_size: int
     @property
     def name(self) -> str: ...
-    def __init__(self, key: bytes, msg: ReadableBuffer | None = ..., digestmod: _DigestMod = ...) -> None: ...
+    def __init__(self, key: bytes | bytearray, msg: ReadableBuffer | None = ..., digestmod: _DigestMod = ...) -> None: ...
     def update(self, msg: ReadableBuffer) -> None: ...
     def digest(self) -> bytes: ...
     def hexdigest(self) -> str: ...
@@ -40,4 +40,4 @@ class HMAC:
 def compare_digest(__a: ReadableBuffer, __b: ReadableBuffer) -> bool: ...
 @overload
 def compare_digest(__a: AnyStr, __b: AnyStr) -> bool: ...
-def digest(key: bytes, msg: ReadableBuffer, digest: _DigestMod) -> bytes: ...
+def digest(key: _BufferWithLen, msg: ReadableBuffer, digest: _DigestMod) -> bytes: ...