diff --git a/aiostd/__init__.py b/aiostd/__init__.py
index 2244ab8..5c54b14 100644
--- a/aiostd/__init__.py
+++ b/aiostd/__init__.py
@@ -1,11 +1,11 @@
 import asyncio
 import os
-from typing import IO
+from typing import IO, Optional
 
 
 async def open_io_stream_reader(
     reader: IO,
-    loop: asyncio.AbstractEventLoop | None = None,
+    loop: Optional[asyncio.AbstractEventLoop] = None,
 ) -> asyncio.StreamReader:
     """
     Asynchronously opens a stream reader for the given IO object.
@@ -34,7 +34,7 @@ async def open_io_stream_reader(
 
 async def open_io_stream_writer(
     writer: IO,
-    loop: asyncio.AbstractEventLoop | None = None,
+    loop: Optional[asyncio.AbstractEventLoop] = None,
 ) -> asyncio.StreamWriter:
     """
     Asynchronously opens a stream writer for the given IO object.
@@ -66,7 +66,7 @@ async def open_io_stream_writer(
 async def open_io_stream(
     reader: IO,
     writer: IO,
-    loop: asyncio.AbstractEventLoop | None = None,
+    loop: Optional[asyncio.AbstractEventLoop] = None,
 ) -> tuple[asyncio.StreamReader, asyncio.StreamWriter]:
     """
     Asynchronously opens both stream reader and writer for the given IO objects.