diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index 48a36a3..57d851c 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -469,7 +469,9 @@
             if "x" in mode:
                 support.unlink(self.filename)
             with open(self.filename, mode) as f:
-                with gzip.GzipFile(fileobj=f) as g:
+                with self.assertWarns(FutureWarning):
+                    g = gzip.GzipFile(fileobj=f)
+                with g:
                     self.assertEqual(g.mode, gzip.WRITE)
 
     def test_bytes_filename(self):