diff --git a/stdlib/builtins.pyi b/stdlib/builtins.pyi
index 92b5279bc..6d2e219e0 100644
--- a/stdlib/builtins.pyi
+++ b/stdlib/builtins.pyi
@@ -203,7 +203,7 @@ class type:
     def __instancecheck__(self, __instance: Any) -> bool: ...
     def __subclasscheck__(self, __subclass: type) -> bool: ...
     @classmethod
-    def __prepare__(metacls, __name: str, __bases: tuple[type, ...], **kwds: Any) -> Mapping[str, object]: ...
+    def __prepare__(metacls, __name: str, __bases: tuple[type, ...], **kwds: Any) -> MutableMapping[str, object]: ...
     if sys.version_info >= (3, 10):
         def __or__(self, __value: Any) -> types.UnionType: ...
         def __ror__(self, __value: Any) -> types.UnionType: ...