diff --git a/stdlib/2/__builtin__.pyi b/stdlib/2/__builtin__.pyi
index 85fa0b120..4b238a383 100644
--- a/stdlib/2/__builtin__.pyi
+++ b/stdlib/2/__builtin__.pyi
@@ -795,6 +795,7 @@ class memoryview(Sized, Container[_mv_container_type]):
     ndim: int
 
     if sys.version_info >= (3,):
+        obj: Union[bytes, bytearray]
         c_contiguous: bool
         f_contiguous: bool
         contiguous: bool
@@ -802,6 +803,7 @@ class memoryview(Sized, Container[_mv_container_type]):
         def __init__(self, obj: Union[bytes, bytearray, memoryview]) -> None: ...
         def __enter__(self) -> memoryview: ...
         def __exit__(self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]) -> None: ...
+        def cast(self, format: str, shape: Union[List[int], Tuple[int]] = ...): ...
     else:
         def __init__(self, obj: Union[bytes, bytearray, buffer, memoryview]) -> None: ...
 
diff --git a/stdlib/2and3/builtins.pyi b/stdlib/2and3/builtins.pyi
index 85fa0b120..4b238a383 100644
--- a/stdlib/2and3/builtins.pyi
+++ b/stdlib/2and3/builtins.pyi
@@ -795,6 +795,7 @@ class memoryview(Sized, Container[_mv_container_type]):
     ndim: int
 
     if sys.version_info >= (3,):
+        obj: Union[bytes, bytearray]
         c_contiguous: bool
         f_contiguous: bool
         contiguous: bool
@@ -802,6 +803,7 @@ class memoryview(Sized, Container[_mv_container_type]):
         def __init__(self, obj: Union[bytes, bytearray, memoryview]) -> None: ...
         def __enter__(self) -> memoryview: ...
         def __exit__(self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]) -> None: ...
+        def cast(self, format: str, shape: Union[List[int], Tuple[int]] = ...): ...
     else:
         def __init__(self, obj: Union[bytes, bytearray, buffer, memoryview]) -> None: ...