diff --git a/testing/acceptance_test.py b/testing/acceptance_test.py
index c074674..22f61c8 100644
--- a/testing/acceptance_test.py
+++ b/testing/acceptance_test.py
@@ -353,18 +353,15 @@ def test_terminate_on_hangingnode(testdir):
     result.stdout.fnmatch_lines(["*killed*my*", ])
 
 
-@pytest.mark.xfail(reason='see #30')
 def test_auto_detect_cpus(testdir, monkeypatch):
     import multiprocessing
-    monkeypatch.setattr(multiprocessing, 'cpu_count', lambda: 3)
+    count = multiprocessing.cpu_count()
     testdir.makeconftest("""
-        def pytest_unconfigure(config):
-            with open('cpus', 'w') as f:
-                f.write('cpus = %s' % config.option.numprocesses)
+        def pytest_configure(config):
+            print("numprocesses: (%s)" % config.getoption("numprocesses"))
     """)
-    testdir.inline_run('-n=auto')
-    cpus_file = testdir.tmpdir.join('cpus')
-    assert cpus_file.read() == 'cpus = 3'
+    result = testdir.runpytest('-n=auto', '-s')
+    result.stdout.fnmatch_lines(["*numprocesses: (%s)*" % count])
 
 
 @pytest.mark.xfail(reason="works if run outside test suite", run=False)