diff --git a/kitty/conf/utils.py b/kitty/conf/utils.py
index 9d241e7a4..e007c175d 100644
--- a/kitty/conf/utils.py
+++ b/kitty/conf/utils.py
@@ -256,7 +256,7 @@ def init_config(default_config_lines: Iterable[str], parse_config: Callable) ->
     return Options, defaults
 
 
-def key_func() -> Tuple[Callable, Dict[str, Callable]]:
+def key_func() -> Tuple[Callable[..., Callable], Dict[str, Callable]]:
     ans: Dict[str, Callable] = {}
 
     def func_with_args(*names: str) -> Callable:
diff --git a/setup.cfg b/setup.cfg
index 2c4646cee..13fc7d90c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -26,6 +26,7 @@ warn_no_return = False
 warn_unused_configs = True
 check_untyped_defs = True
 disallow_untyped_defs = True
+disallow_untyped_decorators = True
 
 [mypy-conf]
 # ignored because on the CI server sphinx type stubs are available somehow, but