diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index a453ccc4909..784f95be9ef 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -445,6 +445,7 @@ def joiningfunc(mainthread):
         p = subprocess.Popen([sys.executable, "-c", script], stdout=subprocess.PIPE)
         rc = p.wait()
         data = p.stdout.read().decode().replace('\r', '')
+        p.stdout.close()
         self.assertEqual(data, "end of main\nend of thread\n")
         self.assertFalse(rc == 2, "interpreter was blocked")
         self.assertTrue(rc == 0, "Unexpected error")