diff --git a/CHANGELOG.md b/CHANGELOG.md
index f015b7d..c5a1247 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.6.6] 2026-08-20
+### Fixed
+- `setup_logging_level` isinstance check.
+
 ## [0.6.5] 2026-08-20
 ### Added
 - `return_single_namespace` option for `parse_args_using_dataclass` function.
diff --git a/CITATION.cff b/CITATION.cff
index 325b383..d361872 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -17,5 +17,5 @@ keywords:
   - tools
   - utilities
 license: MIT
-version: 0.6.5
+version: 0.6.6
 date-released: '2026-08-20'
diff --git a/src/pythonwrench/__init__.py b/src/pythonwrench/__init__.py
index 12a5f82..7075833 100644
--- a/src/pythonwrench/__init__.py
+++ b/src/pythonwrench/__init__.py
@@ -9,7 +9,7 @@
 __license__ = "MIT"
 __maintainer__ = "Étienne Labbé (Labbeti)"
 __status__ = "Development"
-__version__ = "0.6.5"
+__version__ = "0.6.6"
 
 
 from typing import TYPE_CHECKING
diff --git a/src/pythonwrench/logging.py b/src/pythonwrench/logging.py
index c3dda87..2835f5d 100644
--- a/src/pythonwrench/logging.py
+++ b/src/pythonwrench/logging.py
@@ -5,10 +5,11 @@
 import logging
 import sys
 from functools import lru_cache
+from io import TextIOBase
 from logging import FileHandler, Formatter, Logger, StreamHandler
 from pathlib import Path
 from types import ModuleType
-from typing import IO, Iterable, List, Literal, Optional, TypeVar, Union
+from typing import IO, Iterable, List, Literal, Optional, TextIO, TypeVar, Union
 
 from typing_extensions import TypeAlias
 
@@ -117,11 +118,11 @@ def setup_logging_level(
             for handler in logging.getLogger().handlers
             if isinstance(handler, StreamHandler)
         ]
-    elif isinstance(stream, IO):
+    elif isinstance(stream, (TextIOBase, TextIO)):
         streams = [stream]
     elif stream is None:
         streams = stream
-    elif isinstance_generic(stream, Iterable[IO]):
+    elif isinstance_generic(stream, Iterable[Union[TextIOBase, TextIO]]):
         streams = list(stream)
     else:
         raise TypeError(f"Invalid argument type {type(stream)=}.")
diff --git a/tests/test_typing.py b/tests/test_typing.py
index cf5b650..676937a 100644
--- a/tests/test_typing.py
+++ b/tests/test_typing.py
@@ -1,8 +1,11 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+import logging
 import unittest
 from dataclasses import dataclass
+from io import TextIOBase
+from logging import StreamHandler
 from numbers import Number
 from pathlib import Path
 from typing import (
@@ -331,6 +334,18 @@ def test_check_only_first(self) -> None:
         assert isinstance_generic([], List[int], check_only_first=True)
         assert isinstance_generic([1, 2], List, check_only_first=True)
 
+    def test_io_check(self) -> None:
+        assert isinstance_generic([], Iterable[TextIOBase])
+        assert not isinstance_generic([1], Iterable[TextIOBase])
+
+        logger = logging.getLogger()
+        streams = [
+            handler.stream
+            for handler in logger.handlers
+            if isinstance(handler, StreamHandler)
+        ]
+        assert isinstance_generic(streams, Iterable[TextIOBase])
+
 
 class TestCheckArgsType(TestCase):
     def test_example_1(self) -> None: