diff --git a/src/msgspec/json.pyi b/src/msgspec/json.pyi
index a77e656d..456b96a6 100644
--- a/src/msgspec/json.pyi
+++ b/src/msgspec/json.pyi
@@ -1,4 +1,5 @@
 from collections.abc import Callable, Iterable
+from types import GenericAlias
 from typing import (
     Any,
     Generic,
@@ -67,6 +68,7 @@ class Decoder(Generic[_T]):
     ) -> None: ...
     def decode(self, buf: Buffer | str, /) -> _T: ...
     def decode_lines(self, buf: Buffer | str, /) -> list[_T]: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 @overload
 def decode(
diff --git a/src/msgspec/msgpack.pyi b/src/msgspec/msgpack.pyi
index f76c9503..87307665 100644
--- a/src/msgspec/msgpack.pyi
+++ b/src/msgspec/msgpack.pyi
@@ -1,4 +1,5 @@
 from collections.abc import Callable
+from types import GenericAlias
 from typing import (
     Any,
     Generic,
@@ -49,6 +50,7 @@ class Decoder(Generic[_T]):
         ext_hook: _ExtHookSig = None,
     ) -> None: ...
     def decode(self, buf: Buffer, /) -> _T: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
 @final
 class Encoder: