diff --git a/tests/test_offline.py b/tests/test_offline.py
index 09dc0b3fa232b8a9cfe7a6fd73a1ccae8fd18576..281bf83d0f956a19f685b50fea25bba1f3a14c1b 100644
--- a/tests/test_offline.py
+++ b/tests/test_offline.py
@@ -222,8 +222,8 @@ class TestOfflineReader(unittest.TestCase):
         self.assertEqual(float(head['kcut']), 2)
 
         # test the warning for unsupported fheader format
-        self.assertWarns(UserWarning, self.r.header,
-                         "Your file header has an unsupported format")
+        with self.assertWarns(UserWarning):
+            self.r.header
 
 
 class TestOfflineEvents(unittest.TestCase):