diff --git a/third_party/2and3/decorator.pyi b/third_party/2and3/decorator.pyi
index 18c919f87..ee090a6b9 100644
--- a/third_party/2and3/decorator.pyi
+++ b/third_party/2and3/decorator.pyi
@@ -1,8 +1,9 @@
 import sys
-from typing import Any, Callable, Dict, List, NamedTuple, Optional, Pattern, Text, Tuple, TypeVar
+from typing import Any, Callable, Dict, Iterator, List, NamedTuple, Optional, Pattern, Text, Tuple, TypeVar
 
 _C = TypeVar("_C", bound=Callable[..., Any])
 _Func = TypeVar("_Func", bound=Callable[..., Any])
+_T = TypeVar("_T")
 
 def get_init(cls): ...
 
@@ -76,8 +77,8 @@ class FunctionMaker(object):
 def decorate(func: _Func, caller: Callable[..., Any], extras: Any = ...) -> _Func: ...
 def decorator(caller: Callable[..., Any], _func: Optional[Callable[..., Any]] = ...) -> Callable[[_C], _C]: ...
 
-class ContextManager(_GeneratorContextManager[Any]):
+class ContextManager(_GeneratorContextManager[_T]):
     def __call__(self, func: _C) -> _C: ...
 
-def contextmanager(func: _C) -> _C: ...
+def contextmanager(func: Callable[..., Iterator[_T]]) -> Callable[..., ContextManager[_T]]: ...
 def dispatch_on(*dispatch_args: Any) -> Callable[[Callable[..., Any]], Callable[..., Any]]: ...