diff --git a/keystonemiddleware/auth_token/__init__.py b/keystonemiddleware/auth_token/__init__.py
index 89fed656..959a43d8 100644
--- a/keystonemiddleware/auth_token/__init__.py
+++ b/keystonemiddleware/auth_token/__init__.py
@@ -751,9 +751,16 @@ class AuthProtocol(BaseAuthProtocol):
                 self.log.info(_LI('Deferring reject downstream'))
             else:
                 self.log.info(_LI('Rejecting request'))
+                message = 'The request you have made requires authentication.'
+                body = {'error': {
+                    'code': 401,
+                    'title': 'Unauthorized',
+                    'message': message,
+                }}
                 raise webob.exc.HTTPUnauthorized(
-                    body='Authentication required',
-                    headers=self._reject_auth_headers)
+                    body=jsonutils.dumps(body),
+                    headers=self._reject_auth_headers,
+                    content_type='application/json')
 
         if request.user_token_valid:
             user_auth_ref = request.token_auth._user_auth_ref
diff --git a/keystonemiddleware/tests/unit/auth_token/test_auth_token_middleware.py b/keystonemiddleware/tests/unit/auth_token/test_auth_token_middleware.py
index 942f2c03..b2572a0f 100644
--- a/keystonemiddleware/tests/unit/auth_token/test_auth_token_middleware.py
+++ b/keystonemiddleware/tests/unit/auth_token/test_auth_token_middleware.py
@@ -1925,7 +1925,8 @@ class CommonCompositeAuthTests(object):
         resp = self.call_middleware(headers={'X-Auth-Token': token,
                                              'X-Service-Token': service_token},
                                     expected_status=401)
-        self.assertEqual(b'Authentication required', resp.body)
+        expected_body = b'The request you have made requires authentication.'
+        self.assertThat(resp.body, matchers.Contains(expected_body))
 
     def test_composite_auth_no_service_token(self):
         self.purge_service_token_expected_env()
@@ -1952,13 +1953,15 @@ class CommonCompositeAuthTests(object):
         resp = self.call_middleware(headers={'X-Auth-Token': token,
                                              'X-Service-Token': service_token},
                                     expected_status=401)
-        self.assertEqual(b'Authentication required', resp.body)
+        expected_body = b'The request you have made requires authentication.'
+        self.assertThat(resp.body, matchers.Contains(expected_body))
 
     def test_composite_auth_no_user_token(self):
         service_token = self.token_dict['uuid_service_token_default']
         resp = self.call_middleware(headers={'X-Service-Token': service_token},
                                     expected_status=401)
-        self.assertEqual(b'Authentication required', resp.body)
+        expected_body = b'The request you have made requires authentication.'
+        self.assertThat(resp.body, matchers.Contains(expected_body))
 
     def test_composite_auth_delay_ok(self):
         self.middleware._delay_auth_decision = True