diff --git a/setup.cfg b/setup.cfg
index e3cca47..8b0a3bc 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -14,22 +14,22 @@ license       = MIT
 license_files = LICENSE.txt
 
 classifiers =
-	Development Status :: 4 - Beta
-	Intended Audience :: Developers
-	License :: OSI Approved :: MIT License
-	Programming Language :: Python :: 3
-	Programming Language :: Python :: 3.6
-	Programming Language :: Python :: 3.7
-	Programming Language :: Python :: 3.8
-	Programming Language :: Python :: 3.9
-	Programming Language :: Python :: 3.10
-	Programming Language :: Python :: 3.11
-	Programming Language :: Python :: 3.12
-	Topic :: Communications :: Email
-	Topic :: Text Processing :: Markup :: HTML
+    Development Status :: 4 - Beta
+    Intended Audience :: Developers
+    License :: OSI Approved :: MIT License
+    Programming Language :: Python :: 3
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
+    Programming Language :: Python :: 3.11
+    Programming Language :: Python :: 3.12
+    Topic :: Communications :: Email
+    Topic :: Text Processing :: Markup :: HTML
 project_urls =
-	Code = https://github.com/FelixSchwarz/mjml-python
-	Issue tracker = https://github.com/FelixSchwarz/mjml-python/issues
+    Code = https://github.com/FelixSchwarz/mjml-python
+    Issue tracker = https://github.com/FelixSchwarz/mjml-python/issues
 
 
 [options]
@@ -46,7 +46,7 @@ install_requires =
     jinja2
 
 scripts =
-	mjml/scripts/mjml-html-compare
+    mjml/scripts/mjml-html-compare
 
 
 [options.packages.find]
@@ -55,12 +55,12 @@ exclude =
 
 [options.extras_require]
 testing =
-	FakeFSHelpers
-	HTMLCompare >= 0.3.0        # >= 0.3.0: ability to ignore attribute ordering in HTML
-	lxml
-        pytest
+    HTMLCompare >= 0.3.0        # >= 0.3.0: ability to ignore attribute ordering in HTML
+    lxml
+    pytest
 css_inlining =
-	css_inline >= 0.11, < 0.14        # >= 0.11, < 0.14: CSSInliner(inline_style_tags=..., keep_link_tags=..., keep_style_tags=...)
+    # >= 0.11: CSSInliner(inline_style_tags=..., keep_link_tags=..., keep_style_tags=...)
+    css_inline >= 0.11
 
 
 [options.entry_points]
diff --git a/tests/includes_with_umlauts_test.py b/tests/includes_with_umlauts_test.py
index e97bd29..4edc97d 100644
--- a/tests/includes_with_umlauts_test.py
+++ b/tests/includes_with_umlauts_test.py
@@ -1,20 +1,24 @@
 
+import os
+from contextlib import contextmanager
 from io import StringIO
 
-import pytest
-from schwarz.fakefs_helpers import FakeFS
-
 from mjml import mjml_to_html
 
 
-@pytest.fixture
-def fs():
-    _fs = FakeFS.set_up()
-    yield _fs
-    _fs.tear_down()
+# could use "contextlib.chdir" in Python 3.11+
+# https://github.com/python/cpython/commit/3592980f9122ab0d9ed93711347742d110b749c2
+@contextmanager
+def chdir(path):
+    old_chdir = os.getcwd()
+    try:
+        os.chdir(path)
+        yield
+    finally:
+        os.chdir(old_chdir)
 
 
-def test_can_properly_handle_include_umlauts(fs):
+def test_can_properly_handle_include_umlauts(tmp_path):
     included_mjml = (
         '<mj-section>'
         '  <mj-column>'
@@ -30,9 +34,11 @@ def test_can_properly_handle_include_umlauts(fs):
         '  </mj-body>'
         '</mjml>'
     )
-    fs.create_file('footer.mjml', contents=included_mjml.encode('utf8'))
+    path_footer = tmp_path / 'footer.mjml'
+    path_footer.write_text(included_mjml, encoding='utf8')
 
-    result = mjml_to_html(StringIO(mjml))
+    with chdir(tmp_path):
+        result = mjml_to_html(StringIO(mjml))
     html = result.html
 
     assert ('äöüß' in html)