diff --git a/stdlib/3/types.pyi b/stdlib/3/types.pyi
index 2c1c903d6..adc629cbe 100644
--- a/stdlib/3/types.pyi
+++ b/stdlib/3/types.pyi
@@ -79,6 +79,7 @@ class MappingProxyType(Mapping[_KT, _VT], Generic[_KT, _VT]):
     def __len__(self) -> int: ...
 
 class SimpleNamespace:
+    def __init__(self, **kwargs: Any) -> None: ...
     def __getattribute__(self, name: str) -> Any: ...
     def __setattr__(self, name: str, value: Any) -> None: ...
     def __delattr__(self, name: str) -> None: ...