diff --git a/src/core/__tests__/ReactIdentity-test.js b/src/core/__tests__/ReactIdentity-test.js
new file mode 100644
index 0000000000..ecf71a8553
--- /dev/null
+++ b/src/core/__tests__/ReactIdentity-test.js
@@ -0,0 +1,83 @@
+/**
+ * @jsx React.DOM
+ * @emails react-core
+ */
+
+"use strict";
+
+var React;
+var ReactTestUtils;
+var reactComponentExpect;
+
+describe('ReactIdentity', function() {
+
+  beforeEach(function() {
+    require('mock-modules').autoMockOff().dumpCache();
+    React = require('React');
+    ReactTestUtils = require('ReactTestUtils');
+    reactComponentExpect = require('reactComponentExpect');
+  });
+
+  it('should allow keyed objects to express identity', function() {
+    var instance =
+      <div>
+        {{
+          first: <div />,
+          second: <div />
+        }}
+      </div>;
+
+    React.renderComponent(instance, document.createElement('div'));
+    var node = instance.getDOMNode();
+    reactComponentExpect(instance).toBeDOMComponentWithChildCount(2);
+    expect(node.childNodes[0].id).toEqual('.reactRoot[0].:0:first');
+    expect(node.childNodes[1].id).toEqual('.reactRoot[0].:0:second');
+  });
+
+  it('should allow key property to express identity', function() {
+    var instance =
+      <div>
+        <div key="apple" />
+        <div key="banana" />
+      </div>;
+
+    React.renderComponent(instance, document.createElement('div'));
+    var node = instance.getDOMNode();
+    reactComponentExpect(instance).toBeDOMComponentWithChildCount(2);
+    expect(node.childNodes[0].id).toEqual('.reactRoot[0].:apple');
+    expect(node.childNodes[1].id).toEqual('.reactRoot[0].:banana');
+  });
+
+  it('should use instance identity', function() {
+
+    var Wrapper = React.createClass({
+      render: function() {
+        return <a key="i_get_overwritten">{this.props.children}</a>;
+      }
+    });
+
+    var instance =
+      <div>
+        <Wrapper key="wrap1"><span key="squirrel" /></Wrapper>
+        <Wrapper key="wrap2"><span key="bunny" /></Wrapper>
+        <Wrapper><span key="chipmunk" /></Wrapper>
+      </div>;
+
+    React.renderComponent(instance, document.createElement('div'));
+    var node = instance.getDOMNode();
+    reactComponentExpect(instance).toBeDOMComponentWithChildCount(3);
+    expect(node.childNodes[0].id)
+      .toEqual('.reactRoot[0].:wrap1');
+    expect(node.childNodes[0].firstChild.id)
+      .toEqual('.reactRoot[0].:wrap1.:squirrel');
+    expect(node.childNodes[1].id)
+      .toEqual('.reactRoot[0].:wrap2');
+    expect(node.childNodes[1].firstChild.id)
+      .toEqual('.reactRoot[0].:wrap2.:bunny');
+    expect(node.childNodes[2].id)
+      .toEqual('.reactRoot[0].:2');
+    expect(node.childNodes[2].firstChild.id)
+      .toEqual('.reactRoot[0].:2.:chipmunk');
+  });
+
+});
diff --git a/src/utils/flattenChildren.js b/src/utils/flattenChildren.js
index f7a4bd3372..031b86e588 100644
--- a/src/utils/flattenChildren.js
+++ b/src/utils/flattenChildren.js
@@ -51,8 +51,7 @@ var flattenChildrenImpl = function(res, children, nameSoFar) {
   if (Array.isArray(children)) {
     for (var i = 0; i < children.length; i++) {
       var child = children[i];
-      key = child && child.mountInContainerNode &&
-            (child._key || child.props.key);
+      key = child && (child._key || (child.props && child.props.key));
       escapedKey = key ? escapeTextForBrowser(key) : ('' + i);
       flattenChildrenImpl(
         res,