diff --git a/stdlib/3/typing.pyi b/stdlib/3/typing.pyi
index 96eaeeccd..6fb66ad5f 100644
--- a/stdlib/3/typing.pyi
+++ b/stdlib/3/typing.pyi
@@ -339,10 +339,12 @@ class MutableSet(AbstractSet[_T], Generic[_T]):
     def __ixor__(self, s: AbstractSet[_S]) -> MutableSet[Union[_T, _S]]: ...
     def __isub__(self, s: AbstractSet[Any]) -> MutableSet[_T]: ...
 
-class MappingView:
+class MappingView(Sized):
+    def __init__(self, mapping: Mapping[_KT_co, _VT_co]) -> None: ...  # undocumented
     def __len__(self) -> int: ...
 
 class ItemsView(MappingView, AbstractSet[Tuple[_KT_co, _VT_co]], Generic[_KT_co, _VT_co]):
+    def __init__(self, mapping: Mapping[_KT_co, _VT_co]) -> None: ...  # undocumented
     def __and__(self, o: Iterable[Any]) -> Set[Tuple[_KT_co, _VT_co]]: ...
     def __rand__(self, o: Iterable[_T]) -> Set[_T]: ...
     def __contains__(self, o: object) -> bool: ...
@@ -357,6 +359,7 @@ class ItemsView(MappingView, AbstractSet[Tuple[_KT_co, _VT_co]], Generic[_KT_co,
     def __rxor__(self, o: Iterable[_T]) -> Set[Union[Tuple[_KT_co, _VT_co], _T]]: ...
 
 class KeysView(MappingView, AbstractSet[_KT_co], Generic[_KT_co]):
+    def __init__(self, mapping: Mapping[_KT_co, _VT_co]) -> None: ...  # undocumented
     def __and__(self, o: Iterable[Any]) -> Set[_KT_co]: ...
     def __rand__(self, o: Iterable[_T]) -> Set[_T]: ...
     def __contains__(self, o: object) -> bool: ...
@@ -371,6 +374,7 @@ class KeysView(MappingView, AbstractSet[_KT_co], Generic[_KT_co]):
     def __rxor__(self, o: Iterable[_T]) -> Set[Union[_KT_co, _T]]: ...
 
 class ValuesView(MappingView, Iterable[_VT_co], Generic[_VT_co]):
+    def __init__(self, mapping: Mapping[_KT_co, _VT_co]) -> None: ...  # undocumented
     def __contains__(self, o: object) -> bool: ...
     def __iter__(self) -> Iterator[_VT_co]: ...
     if sys.version_info >= (3, 8):