diff --git a/core-xhr.html b/core-xhr.html
index dbc531b..0a7ef4d 100644
--- a/core-xhr.html
+++ b/core-xhr.html
@@ -77,7 +77,13 @@
         for (var n in params) {
           var v = params[n];
           n = encodeURIComponent(n);
-          r.push(v == null ? n : (n + '=' + encodeURIComponent(v)));
+          if (Array.isArray(v)) {
+            v.forEach(function(val) {
+              r.push(val == null ? n : (n + '=' + encodeURIComponent(val)));
+            });
+          } else {
+            r.push(v == null ? n : (n + '=' + encodeURIComponent(v)));
+          }
         }
         return r.join('&');
       },
diff --git a/test/core-ajax-multivalue.html b/test/core-ajax-multivalue.html
new file mode 100644
index 0000000..c56e88b
--- /dev/null
+++ b/test/core-ajax-multivalue.html
@@ -0,0 +1,59 @@
+<!doctype html>
+<!--
+Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
+The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+<html>
+<head>
+  <title>core-ajax</title>
+  <script src="../../webcomponentsjs/webcomponents.js"></script>
+  <script src="../../web-component-tester/browser.js"></script>
+  <link rel="import" href="../core-ajax.html">
+</head>
+<body>
+
+  <core-ajax></core-ajax>
+
+  <script>
+  suite('multivalue', function(){
+    var animationFrameFlush = function(callback) {
+      flush(function(){
+        requestAnimationFrame(function(){
+          flush(callback);
+        });
+      });
+    };
+    var ajax, requests, xhr;
+    suiteSetup(function(done){
+      ajax = document.querySelector("core-ajax");
+      requests = []
+      xhr = sinon.useFakeXMLHttpRequest();
+      xhr.onCreate = function(xhr) {
+        requests.push(xhr);
+      };
+      async.series([
+          function(cb){
+            ajax.url="http://gdata.youtube.com/feeds/api/videos/";
+            ajax.params='{"alt":"json", "q":"chrome", "keywords":["chrome", "browser"]}';
+            ajax.handleAs="json";
+            ajax.auto=true;
+            cb();
+          },
+          animationFrameFlush
+        ], done);
+    });
+    
+    test('Array valued parameters should be properly encoded', function(done) {
+      var req = requests[0];
+      assert.match(req.url, /[?&]keywords=chrome/);
+      assert.match(req.url, /[?&]keywords=browser/);
+      done();
+    });
+  });
+</script>
+</body>
+</html>
diff --git a/test/index.html b/test/index.html
index 93161c3..4e0a19e 100644
--- a/test/index.html
+++ b/test/index.html
@@ -8,9 +8,10 @@
   <body>
     <script>
       WCT.loadSuites([
+        'core-ajax.html',
+        'core-ajax-multivalue.html',
         'core-ajax-progress.html',
         'core-ajax-race.html',
-	      'core-ajax.html'
       ]);
     </script>
   </body>
