diff --git a/stdlib/2/__builtin__.pyi b/stdlib/2/__builtin__.pyi
index b509195b7..cc72f4758 100644
--- a/stdlib/2/__builtin__.pyi
+++ b/stdlib/2/__builtin__.pyi
@@ -907,11 +907,11 @@ class list(MutableSequence[_T], Generic[_T]):
         def __setslice__(self, start: int, stop: int, o: Sequence[_T]) -> None: ...
         def __delslice__(self, start: int, stop: int) -> None: ...
     def __add__(self, x: List[_T]) -> List[_T]: ...
-    def __iadd__(self, x: Iterable[_T]) -> List[_T]: ...
+    def __iadd__(self: _S, x: Iterable[_T]) -> _S: ...
     def __mul__(self, n: int) -> List[_T]: ...
     def __rmul__(self, n: int) -> List[_T]: ...
     if sys.version_info >= (3,):
-        def __imul__(self, n: int) -> List[_T]: ...
+        def __imul__(self: _S, n: int) -> _S: ...
     def __contains__(self, o: object) -> bool: ...
     def __reversed__(self) -> Iterator[_T]: ...
     def __gt__(self, x: List[_T]) -> bool: ...
diff --git a/stdlib/2and3/builtins.pyi b/stdlib/2and3/builtins.pyi
index b509195b7..cc72f4758 100644
--- a/stdlib/2and3/builtins.pyi
+++ b/stdlib/2and3/builtins.pyi
@@ -907,11 +907,11 @@ class list(MutableSequence[_T], Generic[_T]):
         def __setslice__(self, start: int, stop: int, o: Sequence[_T]) -> None: ...
         def __delslice__(self, start: int, stop: int) -> None: ...
     def __add__(self, x: List[_T]) -> List[_T]: ...
-    def __iadd__(self, x: Iterable[_T]) -> List[_T]: ...
+    def __iadd__(self: _S, x: Iterable[_T]) -> _S: ...
     def __mul__(self, n: int) -> List[_T]: ...
     def __rmul__(self, n: int) -> List[_T]: ...
     if sys.version_info >= (3,):
-        def __imul__(self, n: int) -> List[_T]: ...
+        def __imul__(self: _S, n: int) -> _S: ...
     def __contains__(self, o: object) -> bool: ...
     def __reversed__(self) -> Iterator[_T]: ...
     def __gt__(self, x: List[_T]) -> bool: ...