diff --git a/matemat/webserver/test/test_serve.py b/matemat/webserver/test/test_serve.py
index 0c59a0c..5fdc6ec 100644
--- a/matemat/webserver/test/test_serve.py
+++ b/matemat/webserver/test/test_serve.py
@@ -90,6 +90,7 @@ class TestServe(AbstractHttpdTest):
         self.assertIsNone(packet.pagelet)
         # Make sure a 403 header is served
         self.assertEqual(403, packet.statuscode)
+        self.assertNotEqual('This should not be readable', packet.body)
 
     def test_serve_not_found(self):
         # Request a nonexistent resource