diff --git a/falcon/errors.py b/falcon/errors.py
index d54369ba0..4ad95e757 100644
--- a/falcon/errors.py
+++ b/falcon/errors.py
@@ -50,18 +50,18 @@ class HTTPUnauthorized(HTTPError):
         title (str): Error title (e.g., 'Authentication Required').
         description (str): Human-friendly description of the error, along with
             a helpful suggestion or two.
-        scheme (str): Authentication scheme to use as the value of the
-            WWW-Authenticate header in the response (default ``None``).
+        challenges (iterable of str): One or more authentication
+            challenges to use as the value of the WWW-Authenticate header in
+            the response.
         kwargs (optional): Same as for ``HTTPError``.
 
     """
 
-    def __init__(self, title, description, **kwargs):
+    def __init__(self, title, description, challenges, **kwargs):
         headers = kwargs.setdefault('headers', {})
 
-        scheme = kwargs.pop('scheme', None)
-        if scheme is not None:
-            headers['WWW-Authenticate'] = scheme
+        if challenges:
+            headers['WWW-Authenticate'] = ', '.join(challenges)
 
         super(HTTPUnauthorized, self).__init__(status.HTTP_401, title,
                                                description, **kwargs)
diff --git a/tests/test_httperror.py b/tests/test_httperror.py
index 438fd7d89..fd04bc044 100644
--- a/tests/test_httperror.py
+++ b/tests/test_httperror.py
@@ -74,14 +74,17 @@ class UnauthorizedResource:
     def on_get(self, req, resp):
         raise falcon.HTTPUnauthorized('Authentication Required',
                                       'Missing or invalid token header.',
-                                      scheme='Token; UUID')
+                                      ['Basic realm="simple"'])
 
+    def on_post(self, req, resp):
+        raise falcon.HTTPUnauthorized('Authentication Required',
+                                      'Missing or invalid token header.',
+                                      ['Newauth realm="apps"',
+                                       'Basic realm="simple"'])
 
-class UnauthorizedResourceSchemaless:
-
-    def on_get(self, req, resp):
+    def on_put(self, req, resp):
         raise falcon.HTTPUnauthorized('Authentication Required',
-                                      'Missing or invalid token header.')
+                                      'Missing or invalid token header.', [])
 
 
 class NotFoundResource:
@@ -454,15 +457,20 @@ def test_401(self):
         self.simulate_request('/401')
 
         self.assertEqual(self.srmock.status, falcon.HTTP_401)
-        self.assertIn(('www-authenticate', 'Token; UUID'),
+        self.assertIn(('www-authenticate', 'Basic realm="simple"'),
                       self.srmock.headers)
 
-    def test_401_schemaless(self):
-        self.api.add_route('/401', UnauthorizedResourceSchemaless())
-        self.simulate_request('/401')
+        self.simulate_request('/401', method='POST')
+
+        self.assertEqual(self.srmock.status, falcon.HTTP_401)
+        self.assertIn(('www-authenticate', 'Newauth realm="apps", '
+                      'Basic realm="simple"'),
+                      self.srmock.headers)
+
+        self.simulate_request('/401', method='PUT')
 
         self.assertEqual(self.srmock.status, falcon.HTTP_401)
-        self.assertNotIn(('www-authenticate', 'Token'), self.srmock.headers)
+        self.assertNotIn(('www-authenticate', []), self.srmock.headers)
 
     def test_404_without_body(self):
         self.api.add_route('/404', NotFoundResource())