diff --git a/lib/http-proxy/passes/web-outgoing.js b/lib/http-proxy/passes/web-outgoing.js
index 9281c4a45..64ce20ded 100644
--- a/lib/http-proxy/passes/web-outgoing.js
+++ b/lib/http-proxy/passes/web-outgoing.js
@@ -55,7 +55,11 @@ var passes = exports;
    */
   function writeHeaders(req, res, proxyRes) {
     Object.keys(proxyRes.headers).forEach(function(key) {
-      res.setHeader(key, proxyRes.headers[key]);
+      var v = proxyRes.headers[key]
+      if(key == 'www-authenticate'){
+        v = v.split(',');
+      }
+      res.setHeader(key, v);
     });
   },