diff --git a/aiogram/dispatcher/filters/builtin.py b/aiogram/dispatcher/filters/builtin.py
index 0a81998a..2334b343 100644
--- a/aiogram/dispatcher/filters/builtin.py
+++ b/aiogram/dispatcher/filters/builtin.py
@@ -12,6 +12,19 @@ from aiogram.dispatcher.filters.filters import BoundFilter, Filter
 from aiogram.types import CallbackQuery, Message, InlineQuery, Poll, ChatType
 
 
+IDFilterArgumentType = typing.Union[typing.Iterable[typing.Union[int, str]], str, int]
+
+
+def extract_filter_ids(id_filter_argument: IDFilterArgumentType) -> typing.List[int]:
+    # since "str" is also an "Iterable", we have to check for it first
+    if isinstance(id_filter_argument, str):
+        return [int(id_filter_argument)]
+    if isinstance(id_filter_argument, Iterable):
+        return [int(item) for (item) in id_filter_argument]
+    # the last possible type is a single "int"
+    return [id_filter_argument]
+
+
 class Command(Filter):
     """
     You can handle commands by using this filter.
@@ -543,12 +556,11 @@ class ExceptionsFilter(BoundFilter):
         except:
             return False
 
-
 class IDFilter(Filter):
 
     def __init__(self,
-                 user_id: Optional[Union[Iterable[Union[int, str]], str, int]] = None,
-                 chat_id: Optional[Union[Iterable[Union[int, str]], str, int]] = None,
+                 user_id: Optional[IDFilterArgumentType] = None,
+                 chat_id: Optional[IDFilterArgumentType] = None,
                  ):
         """
         :param user_id:
@@ -557,18 +569,14 @@ class IDFilter(Filter):
         if user_id is None and chat_id is None:
             raise ValueError("Both user_id and chat_id can't be None")
 
-        self.user_id = None
-        self.chat_id = None
+        self.user_id: Optional[IDFilterArgumentType] = None
+        self.chat_id: Optional[IDFilterArgumentType] = None
+
         if user_id:
-            if isinstance(user_id, Iterable):
-                self.user_id = list(map(int, user_id))
-            else:
-                self.user_id = [int(user_id), ]
+            self.user_id = extract_filter_ids(user_id)
+
         if chat_id:
-            if isinstance(chat_id, Iterable):
-                self.chat_id = list(map(int, chat_id))
-            else:
-                self.chat_id = [int(chat_id), ]
+            self.chat_id = extract_filter_ids(chat_id)
 
     @classmethod
     def validate(cls, full_config: typing.Dict[str, typing.Any]) -> typing.Optional[typing.Dict[str, typing.Any]]: