diff --git a/Lib/unittest/test/test_program.py b/Lib/unittest/test/test_program.py
index a50a2452c2c..d5d0f5a71c1 100644
--- a/Lib/unittest/test/test_program.py
+++ b/Lib/unittest/test/test_program.py
@@ -189,7 +189,7 @@ def testWarning(self):
         class FakeTP(unittest.TestProgram):
             def parseArgs(self, *args, **kw): pass
             def runTests(self, *args, **kw): pass
-        warnoptions = sys.warnoptions
+        warnoptions = sys.warnoptions[:]
         try:
             sys.warnoptions[:] = []
             # no warn options, no arg -> default