diff --git a/stdlib/2.7/functools.pyi b/stdlib/2.7/functools.pyi
index c1637643e..884076578 100644
--- a/stdlib/2.7/functools.pyi
+++ b/stdlib/2.7/functools.pyi
@@ -24,7 +24,7 @@ def update_wrapper(wrapper: _AnyCallable, wrapped: _AnyCallable, assigned: Seque
                    updated: Sequence[str] = ...) -> None: ...
 def wraps(wrapped: _AnyCallable, assigned: Sequence[str] = ..., updated: Sequence[str] = ...) -> Callable[[_AnyCallable], _AnyCallable]: ...
 def total_ordering(cls: type) -> type: ...
-def cmp_to_key(mycmp: Callable[[_T, _T], bool]) -> Callable[[_T], Any]: ...
+def cmp_to_key(mycmp: Callable[[_T, _T], int]) -> Callable[[_T], Any]: ...
 
 class partial(Generic[_T]):
     func = ...  # Callable[..., _T]
diff --git a/stdlib/3/functools.pyi b/stdlib/3/functools.pyi
index 0982cfebd..2bd79ef71 100644
--- a/stdlib/3/functools.pyi
+++ b/stdlib/3/functools.pyi
@@ -40,7 +40,7 @@ def update_wrapper(wrapper: _AnyCallable, wrapped: _AnyCallable, assigned: Seque
                    updated: Sequence[str] = ...) -> None: ...
 def wraps(wrapped: _AnyCallable, assigned: Sequence[str] = ..., updated: Sequence[str] = ...) -> Callable[[_AnyCallable], _AnyCallable]: ...
 def total_ordering(cls: type) -> type: ...
-def cmp_to_key(mycmp: Callable[[_T, _T], bool]) -> Callable[[_T], Any]: ...
+def cmp_to_key(mycmp: Callable[[_T, _T], int]) -> Callable[[_T], Any]: ...
 
 class partial(Generic[_T]):
     func = ...  # Callable[..., _T]