diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index b67eed5077f..c7cf24b490e 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -1006,6 +1006,9 @@ class Win32KillTests(unittest.TestCase):
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE,
                                 stdin=subprocess.PIPE)
+        self.addCleanup(proc.stdout.close)
+        self.addCleanup(proc.stderr.close)
+        self.addCleanup(proc.stdin.close)
 
         count, max = 0, 100
         while count < max and proc.poll() is None: