diff --git a/aiogram/dispatcher/event/handler.py b/aiogram/dispatcher/event/handler.py
index 2b71eed5..f20c986b 100644
--- a/aiogram/dispatcher/event/handler.py
+++ b/aiogram/dispatcher/event/handler.py
@@ -21,19 +21,22 @@ CallbackType = Callable[..., Any]
 class CallableMixin:
     callback: CallbackType
     awaitable: bool = field(init=False)
-    spec: inspect.FullArgSpec = field(init=False)
+    params: set[str] = field(init=False)
+    varkw: bool = field(init=False)
 
     def __post_init__(self) -> None:
         callback = inspect.unwrap(self.callback)
         self.awaitable = inspect.isawaitable(callback) or inspect.iscoroutinefunction(callback)
-        self.spec = inspect.getfullargspec(callback)
+        spec = inspect.getfullargspec(callback)
+        self.params = {*spec.args, *spec.kwonlyargs}
+        self.varkw = spec.varkw is not None
 
     def _prepare_kwargs(self, kwargs: Dict[str, Any]) -> Dict[str, Any]:
-        if self.spec.varkw:
+        if self.varkw:
             return kwargs
 
         return {
-            k: v for k, v in kwargs.items() if k in self.spec.args or k in self.spec.kwonlyargs
+            k: kwargs[k] for k in self.params if k in kwargs
         }
 
     async def call(self, *args: Any, **kwargs: Any) -> Any:
diff --git a/tests/test_dispatcher/test_event/test_handler.py b/tests/test_dispatcher/test_event/test_handler.py
index f7000d8e..0c59aff4 100644
--- a/tests/test_dispatcher/test_event/test_handler.py
+++ b/tests/test_dispatcher/test_event/test_handler.py
@@ -1,5 +1,5 @@
 import functools
-from typing import Any, Dict, Union
+from typing import Any, Dict, Union, Callable
 
 import pytest
 from magic_filter import F as A
@@ -61,9 +61,9 @@ class TestCallableMixin:
             pytest.param(SyncCallable(), {"self", "foo", "bar", "baz"}),
         ],
     )
-    def test_init_args_spec(self, callback, args):
+    def test_init_args_spec(self, callback: Callable, args: set[str]):
         obj = CallableMixin(callback)
-        assert set(obj.spec.args) == args
+        assert set(obj.params) == args
 
     def test_init_decorated(self):
         def decorator(func):
@@ -85,9 +85,9 @@ class TestCallableMixin:
         obj1 = CallableMixin(callback1)
         obj2 = CallableMixin(callback2)
 
-        assert set(obj1.spec.args) == {"foo", "bar", "baz"}
+        assert set(obj1.params) == {"foo", "bar", "baz"}
         assert obj1.callback == callback1
-        assert set(obj2.spec.args) == {"foo", "bar", "baz"}
+        assert set(obj2.params) == {"foo", "bar", "baz"}
         assert obj2.callback == callback2
 
     @pytest.mark.parametrize(
@@ -124,7 +124,12 @@ class TestCallableMixin:
             ),
         ],
     )
-    def test_prepare_kwargs(self, callback, kwargs, result):
+    def test_prepare_kwargs(
+        self,
+        callback: Callable,
+        kwargs: Dict[str, Any],
+        result: Dict[str, Any]
+    ):
         obj = CallableMixin(callback)
         assert obj._prepare_kwargs(kwargs) == result