diff --git a/aiogram/dispatcher/event/telegram.py b/aiogram/dispatcher/event/telegram.py
index d3d66305..cb31fea7 100644
--- a/aiogram/dispatcher/event/telegram.py
+++ b/aiogram/dispatcher/event/telegram.py
@@ -40,7 +40,7 @@ class TelegramEventObserver:
         """
         Register filter for all handlers of this event observer
 
-        :param filters: positional filters 
+        :param filters: positional filters
         :param bound_filters: keyword filters
         """
         resolved_filters = self.resolve_filters(bound_filters)
@@ -191,7 +191,8 @@ class TelegramEventObserver:
         return wrapper
 
     def middleware(
-        self, middleware: Optional[MiddlewareType] = None,
+        self,
+        middleware: Optional[MiddlewareType] = None,
     ) -> Union[Callable[[MiddlewareType], MiddlewareType], MiddlewareType]:
         """
         Decorator for registering inner middlewares
@@ -221,7 +222,8 @@ class TelegramEventObserver:
         return wrapper(middleware)
 
     def outer_middleware(
-        self, middleware: Optional[MiddlewareType] = None,
+        self,
+        middleware: Optional[MiddlewareType] = None,
     ) -> Union[Callable[[MiddlewareType], MiddlewareType], MiddlewareType]:
         """
         Decorator for registering outer middlewares