diff --git a/ansible_mitogen/affinity.py b/ansible_mitogen/affinity.py
index 09a6acee..94539e21 100644
--- a/ansible_mitogen/affinity.py
+++ b/ansible_mitogen/affinity.py
@@ -177,9 +177,9 @@ class FixedPolicy(Policy):
     cores, before reusing the second hyperthread of an existing core.
 
     A hook is installed that causes :meth:`reset` to run in the child of any
-    process created with :func:`mitogen.parent.detach_popen`, ensuring
-    CPU-intensive children like SSH are not forced to share the same core as
-    the (otherwise potentially very busy) parent.
+    process created with :func:`mitogen.parent.popen`, ensuring CPU-intensive
+    children like SSH are not forced to share the same core as the (otherwise
+    potentially very busy) parent.
     """
     def __init__(self, cpu_count=None):
         #: For tests.
diff --git a/tests/ansible/tests/affinity_test.py b/tests/ansible/tests/affinity_test.py
index 8ee96085..641455bd 100644
--- a/tests/ansible/tests/affinity_test.py
+++ b/tests/ansible/tests/affinity_test.py
@@ -199,10 +199,10 @@ class LinuxPolicyTest(testlib.TestCase):
             self.policy._set_cpu(3)
             my_cpu = self._get_cpus()
 
-            pid = mitogen.parent.detach_popen(
+            proc = mitogen.parent.popen(
                 args=['cp', '/proc/self/status', tf.name]
             )
-            os.waitpid(pid, 0)
+            proc.wait()
 
             his_cpu = self._get_cpus(tf.name)
             self.assertNotEquals(my_cpu, his_cpu)