diff --git a/src/darker/black_compat.py b/src/darker/black_compat.py
index b5c8e2749..81ad542c2 100644
--- a/src/darker/black_compat.py
+++ b/src/darker/black_compat.py
@@ -19,6 +19,3 @@ def find_project_root(srcs: Sequence[str]) -> Path:
         return cast(Tuple[Path], root)[0]
     # Black < 22
     return cast(Path, root)
-
-
-find_project_root.cache_clear = black_find_project_root.cache_clear
diff --git a/src/darker/tests/conftest.py b/src/darker/tests/conftest.py
index 10e72b157..a2b844ac1 100644
--- a/src/darker/tests/conftest.py
+++ b/src/darker/tests/conftest.py
@@ -6,8 +6,8 @@
 from typing import Dict, Optional
 
 import pytest
+from black import find_project_root as black_find_project_root
 
-from darker.black_compat import find_project_root
 from darker.git import _git_check_output_lines
 
 
@@ -97,5 +97,11 @@ def git_repo(tmp_path, monkeypatch):
 
 @pytest.fixture
 def find_project_root_cache_clear():
-    """Clear LRU caching in :func:`black.find_project_root` before each test"""
-    find_project_root.cache_clear()
+    """Clear LRU caching in :func:`black.find_project_root` before each test
+
+    NOTE: We use `darker.black_compat.find_project_root` to wrap Black's original
+    function since its signature has changed along the way. However, clearing the cache
+    needs to be done on the original of course.
+
+    """
+    black_find_project_root.cache_clear()
diff --git a/src/darker/tests/test_import_sorting.py b/src/darker/tests/test_import_sorting.py
index ecb676748..266574a5f 100644
--- a/src/darker/tests/test_import_sorting.py
+++ b/src/darker/tests/test_import_sorting.py
@@ -7,7 +7,6 @@
 import pytest
 
 import darker.import_sorting
-from darker.black_compat import find_project_root
 from darker.tests.helpers import isort_present
 from darker.utils import TextDocument
 
@@ -76,9 +75,15 @@ def test_apply_isort(encoding, newline):
         ),
     ),
 )
-def test_isort_config(monkeypatch, tmpdir, line_length, settings_file, expect):
+def test_isort_config(
+    monkeypatch,
+    tmpdir,
+    find_project_root_cache_clear,
+    line_length,
+    settings_file,
+    expect,
+):
     """``apply_isort()`` parses ``pyproject.toml``correctly"""
-    find_project_root.cache_clear()
     monkeypatch.chdir(tmpdir)
     (tmpdir / "pyproject.toml").write(
         dedent(
diff --git a/src/darker/tests/test_main.py b/src/darker/tests/test_main.py
index 1277c5222..e385ac25d 100644
--- a/src/darker/tests/test_main.py
+++ b/src/darker/tests/test_main.py
@@ -15,7 +15,6 @@
 import darker.__main__
 import darker.import_sorting
 import darker.linting
-from darker.black_compat import find_project_root
 from darker.exceptions import MissingPackageError
 from darker.git import WORKTREE, RevisionRange
 from darker.tests.helpers import isort_present
@@ -38,9 +37,7 @@ def test_isort_option_without_isort(git_repo, caplog):
 
 
 @pytest.fixture
-def run_isort(git_repo, monkeypatch, caplog, request):
-    find_project_root.cache_clear()
-
+def run_isort(git_repo, monkeypatch, caplog, request, find_project_root_cache_clear):
     monkeypatch.chdir(git_repo.root)
     paths = git_repo.add({"test1.py": "original"}, commit="Initial commit")
     paths["test1.py"].write_bytes(b"changed")