diff --git a/js/src/builtin/Object.js b/js/src/builtin/Object.js
index 50790cdb358f..a7440aec7298 100644
--- a/js/src/builtin/Object.js
+++ b/js/src/builtin/Object.js
@@ -60,7 +60,8 @@ function ObjectGetOwnPropertyDescriptors(O) {
         var desc = std_Object_getOwnPropertyDescriptor(obj, key);
 
         // Step 4.c.
-        _DefineDataProperty(descriptors, key, desc);
+        if (typeof desc !== "undefined")
+            _DefineDataProperty(descriptors, key, desc);
     }
 
     // Step 5.
diff --git a/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/duplicate-keys.js b/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/duplicate-keys.js
index 88d844cd6dd7..371c6c1da70f 100644
--- a/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/duplicate-keys.js
+++ b/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/duplicate-keys.js
@@ -27,5 +27,12 @@ var proxy = new Proxy({}, {
 
 var result = Object.getOwnPropertyDescriptors(proxy);
 assert.sameValue(result.hasOwnProperty('DUPLICATE'), true);
-assert.sameValue(result.DUPLICATE, undefined);
+
+var lastDescriptor = descriptors[descriptors.length - 1];
+assert.notSameValue(result.DUPLICATE, lastDescriptor);
+assert.sameValue(result.DUPLICATE.enumerable, lastDescriptor.enumerable);
+assert.sameValue(result.DUPLICATE.configurable, lastDescriptor.configurable);
+assert.sameValue(result.DUPLICATE.value, lastDescriptor.value);
+assert.sameValue(result.DUPLICATE.writable, lastDescriptor.writable);
+
 assert.sameValue(log, 'ownKeys|getOwnPropertyDescriptor:DUPLICATE|getOwnPropertyDescriptor:DUPLICATE|getOwnPropertyDescriptor:DUPLICATE|');
diff --git a/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/proxy-undefined-descriptor.js b/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/proxy-undefined-descriptor.js
new file mode 100644
index 000000000000..6eb6c7071330
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/proxy-undefined-descriptor.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2016 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Object.getOwnPropertyDescriptors should filter out undefined OwnPropertyDescriptors
+esid: sec-object.getownpropertydescriptors
+author: Jordan Harband
+featurewws: [Proxy]
+includes: [proxyTrapsHelper.js]
+---*/
+
+var key = "a";
+var ownKeys = [key];
+var badProxyHandlers = {
+  getOwnPropertyDescriptor: function () {},
+  ownKeys: function () {
+    return ownKeys;
+  }
+};
+var proxy = new Proxy({}, badProxyHandlers);
+
+var keys = Reflect.ownKeys(proxy);
+assert.notSameValue(keys, ownKeys, 'Object.keys returns a new Array');
+assert.sameValue(Array.isArray(keys), true, 'Object.keys returns an Array');
+assert.sameValue(keys.length, ownKeys.length, 'keys and ownKeys have the same length');
+assert.sameValue(keys[0], ownKeys[0], 'keys and ownKeys have the same contents');
+
+var descriptor = Object.getOwnPropertyDescriptor(proxy, key);
+assert.sameValue(descriptor, undefined, "Descriptor matches result of [[GetOwnPropertyDescriptor]] trap");
+
+var result = Object.getOwnPropertyDescriptors(proxy);
+assert.sameValue(key in result, false, "key is not present in result");
diff --git a/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/shell.js b/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/shell.js
index 4e579ebb7bed..6ed766e9415f 100644
--- a/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/shell.js
+++ b/js/src/tests/test262/built-ins/Object/getOwnPropertyDescriptors/shell.js
@@ -1,5 +1,14 @@
 var assert = {
     sameValue: assertEq,
+    notSameValue(a, b, msg) {
+      try {
+        assertEq(a, b);
+        throw "equal"
+      } catch (e) {
+        if (e === "equal")
+          throw new Error("Assertion failed: expected different values, got " + a);
+      }
+    },
     throws(ctor, f) {
       var fullmsg;
       try {