diff --git a/stdlib/2/__builtin__.pyi b/stdlib/2/__builtin__.pyi
index 7a8425879392..16759dbd02a1 100644
--- a/stdlib/2/__builtin__.pyi
+++ b/stdlib/2/__builtin__.pyi
@@ -28,7 +28,7 @@ class object:
     __doc__ = ...  # type: Optional[str]
     __class__ = ...  # type: type
     __dict__ = ...  # type: Dict[str, Any]
-    __slots__ = ...  # type: Optional[Union[str, unicode, Iterable[Union[str, unicode]]]]
+    __slots__ = ...  # type: Union[str, unicode, Iterable[Union[str, unicode]]]
     __module__ = ...  # type: str
 
     def __init__(self) -> None: ...
diff --git a/stdlib/3/builtins.pyi b/stdlib/3/builtins.pyi
index 8bdeff309fb1..bb2f40a6f14c 100644
--- a/stdlib/3/builtins.pyi
+++ b/stdlib/3/builtins.pyi
@@ -30,7 +30,7 @@ class object:
     __doc__ = ...  # type: Optional[str]
     __class__ = ...  # type: type
     __dict__ = ...  # type: Dict[str, Any]
-    __slots__ = ...  # type: Optional[Union[str, Iterable[str]]]
+    __slots__ = ...  # type: Union[str, Iterable[str]]
     __module__ = ...  # type: str
     if sys.version_info >= (3, 6):
         __annotations__ = ...  # type: Dict[str, Any]