diff --git a/testing/test_config.py b/testing/test_config.py
index 93b288215..9881a5d41 100644
--- a/testing/test_config.py
+++ b/testing/test_config.py
@@ -845,7 +845,7 @@ class TestOverrideIniArgs(object):
             assert inifile is None
 
     def test_addopts_before_initini(self, testdir, tmpdir, monkeypatch):
-        cache_dir = testdir.tmpdir.join('.custom_cache')
+        cache_dir = '.custom_cache'
         monkeypatch.setenv('PYTEST_ADDOPTS', '-o cache_dir=%s' % cache_dir)
         from _pytest.config import get_config
         config = get_config()