diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 72f1c1b..1d5f11c 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -1506,6 +1506,7 @@
                         raise
 
 
+@support.reap_threads
 def test_main():
     support.run_unittest(
         FileTests,