diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
index eb2f72e..030d564 100644
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -100,6 +100,9 @@
         self.assertRaises(ValueError, BZ2File, os.devnull, compresslevel=0)
         self.assertRaises(ValueError, BZ2File, os.devnull, compresslevel=10)
 
+        # compresslevel is keyword-only
+        self.assertRaises(TypeError, BZ2File, os.devnull, "r", 3)
+
     def testRead(self):
         self.createTempFile()
         with BZ2File(self.filename) as bz2f: