diff --git a/tests/unit/test_wheel.py b/tests/unit/test_wheel.py
index 247e8d6643c..e21c0ec2e68 100644
--- a/tests/unit/test_wheel.py
+++ b/tests/unit/test_wheel.py
@@ -422,7 +422,7 @@ def test_install_prefix(self, data, tmpdir):
             self.name,
             user=False,
             home=None,
-            root=tmpdir,
+            root=str(tmpdir),  # Casting needed for CPython 3.10+. See GH-10358.
             isolated=False,
             prefix=prefix,
         )