diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index f5c34f2..0464dba 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -21,7 +21,7 @@ jobs:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2
       with:
         fetch-depth: 0
-    - uses: actions/setup-python@8d9ed9ac5c53483de85588cdf95a591a75ab9f55  # v5.5.0
+    - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065  # v5.6.0
       with:
         python-version: '3.10'
 
diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
index 206dd93..5574b50 100644
--- a/.github/workflows/python-tests.yml
+++ b/.github/workflows/python-tests.yml
@@ -79,7 +79,7 @@ jobs:
       with:
         fetch-depth: 0
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@8d9ed9ac5c53483de85588cdf95a591a75ab9f55  # v5.5.0
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065  # v5.6.0
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install Tox
diff --git a/tests/test_encoding.py b/tests/test_encoding.py
index 0319e9f..8215299 100644
--- a/tests/test_encoding.py
+++ b/tests/test_encoding.py
@@ -7,6 +7,7 @@
 import pytest
 
 pytest_plugins = ["pytester"]
+IS_CI = os.getenv("CI", "false") == "true"
 
 
 @pytest.fixture(
@@ -132,7 +133,7 @@ def test_basic_file_encoding_overwrite(testdir, basic_file, charset, ini_file):
     assert expected in Path(file).read_text(encoding)
 
 
-@pytest.mark.skipif(os.getenv("CI", False), reason="skip on CI")
+@pytest.mark.skipif(IS_CI, reason="skip on CI")
 def test_legacy_diff(testdir, capsys, basic_file, charset):
     """
     Legacy test are supported to fail on Windows, when no encoding is provided.
@@ -158,7 +159,7 @@ def test_legacy_diff(testdir, capsys, basic_file, charset):
     assert diff in stdout
 
 
-@pytest.mark.skipif(os.getenv("CI", False), reason="skip on CI")
+@pytest.mark.skipif(IS_CI, reason="skip on CI")
 def test_legacy_overwrite(testdir, basic_file, charset):
     """
     Legacy test are supported to fail on Windows, when no encoding is provided.
diff --git a/tox.ini b/tox.ini
index d81ccfe..ade7ec9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,6 +9,7 @@ isolated_build = true
 
 [testenv]
 changedir = .tmp/{envname}
+passenv = HOME,WINDIR,LC_ALL,LC_CTYPE,CI
 setenv =
     numpydev: PIP_EXTRA_INDEX_URL = https://pypi.anaconda.org/scientific-python-nightly-wheels/simple
 description = run tests