diff --git a/stdlib/2/__builtin__.pyi b/stdlib/2/__builtin__.pyi
index e19b65c2e..680f1fd7b 100644
--- a/stdlib/2/__builtin__.pyi
+++ b/stdlib/2/__builtin__.pyi
@@ -667,6 +667,8 @@ class bytearray(MutableSequence[int], ByteString):
     def decode(self, encoding: Text = ..., errors: Text = ...) -> str: ...
     def endswith(self, suffix: Union[bytes, Tuple[bytes, ...]]) -> bool: ...
     def expandtabs(self, tabsize: int = ...) -> bytearray: ...
+    if sys.version_info < (3,):
+        def extend(self, iterable: Union[str, Iterable[int]]) -> None: ...
     if sys.version_info >= (3,):
         def find(self, sub: Union[bytes, int], start: Optional[int] = ..., end: Optional[int] = ...) -> int: ...
         if sys.version_info >= (3, 5):
diff --git a/stdlib/2and3/builtins.pyi b/stdlib/2and3/builtins.pyi
index e19b65c2e..680f1fd7b 100644
--- a/stdlib/2and3/builtins.pyi
+++ b/stdlib/2and3/builtins.pyi
@@ -667,6 +667,8 @@ class bytearray(MutableSequence[int], ByteString):
     def decode(self, encoding: Text = ..., errors: Text = ...) -> str: ...
     def endswith(self, suffix: Union[bytes, Tuple[bytes, ...]]) -> bool: ...
     def expandtabs(self, tabsize: int = ...) -> bytearray: ...
+    if sys.version_info < (3,):
+        def extend(self, iterable: Union[str, Iterable[int]]) -> None: ...
     if sys.version_info >= (3,):
         def find(self, sub: Union[bytes, int], start: Optional[int] = ..., end: Optional[int] = ...) -> int: ...
         if sys.version_info >= (3, 5):