diff --git a/src/core/ReactComponent.js b/src/core/ReactComponent.js
index fe704dfbbf..b9aa2330c4 100644
--- a/src/core/ReactComponent.js
+++ b/src/core/ReactComponent.js
@@ -188,6 +188,17 @@ var ReactComponent = {
    */
   Mixin: {
 
+    /**
+     * Checks whether or not this component is mounted.
+     *
+     * @return {boolean} True if mounted, false otherwise.
+     * @final
+     * @protected
+     */
+    isMounted: function() {
+      return this._lifeCycleState === ComponentLifeCycle.MOUNTED;
+    },
+
     /**
      * Returns the DOM node rendered by this component.
      *
@@ -201,7 +212,7 @@ var ReactComponent = {
         'getDOMNode(): The DOM is not supported in the current environment.'
       );
       invariant(
-        this._lifeCycleState === ComponentLifeCycle.MOUNTED,
+        this.isMounted(),
         'getDOMNode(): A component must be mounted to have a DOM node.'
       );
       var rootNode = this._rootNode;
@@ -329,7 +340,7 @@ var ReactComponent = {
      */
     mountComponent: function(rootID, transaction) {
       invariant(
-        this._lifeCycleState === ComponentLifeCycle.UNMOUNTED,
+        !this.isMounted(),
         'mountComponent(%s, ...): Can only mount an unmounted component.',
         rootID
       );
@@ -354,7 +365,7 @@ var ReactComponent = {
      */
     unmountComponent: function() {
       invariant(
-        this._lifeCycleState === ComponentLifeCycle.MOUNTED,
+        this.isMounted(),
         'unmountComponent(): Can only unmount a mounted component.'
       );
       var props = this.props;
@@ -378,7 +389,7 @@ var ReactComponent = {
      */
     receiveProps: function(nextProps, transaction) {
       invariant(
-        this._lifeCycleState === ComponentLifeCycle.MOUNTED,
+        this.isMounted(),
         'receiveProps(...): Can only update a mounted component.'
       );
       var props = this.props;
diff --git a/src/core/ReactCompositeComponent.js b/src/core/ReactCompositeComponent.js
index cfbe109833..3fed7ad324 100644
--- a/src/core/ReactCompositeComponent.js
+++ b/src/core/ReactCompositeComponent.js
@@ -548,7 +548,7 @@ var ReactCompositeComponentMixin = {
   replaceState: function(completeState) {
     var compositeLifeCycleState = this._compositeLifeCycleState;
     invariant(
-      this._lifeCycleState === ReactComponent.LifeCycle.MOUNTED ||
+      this.isMounted() ||
       compositeLifeCycleState === CompositeLifeCycle.MOUNTING,
       'replaceState(...): Can only update a mounted (or mounting) component.'
     );
@@ -712,7 +712,7 @@ var ReactCompositeComponentMixin = {
   forceUpdate: function() {
     var compositeLifeCycleState = this._compositeLifeCycleState;
     invariant(
-      this._lifeCycleState === ReactComponent.LifeCycle.MOUNTED,
+      this.isMounted(),
       'forceUpdate(...): Can only force an update on mounted components.'
     );
     invariant(
diff --git a/src/core/__tests__/ReactNativeComponent-test.js b/src/core/__tests__/ReactNativeComponent-test.js
index ee7e986593..54e4bc5504 100644
--- a/src/core/__tests__/ReactNativeComponent-test.js
+++ b/src/core/__tests__/ReactNativeComponent-test.js
@@ -241,17 +241,21 @@ describe('ReactNativeComponent', function() {
 
       var mixInto = require('mixInto');
       var ReactComponent = require('ReactComponent');
+      var ReactMultiChild = require('ReactMultiChild');
       var ReactNativeComponent = require('ReactNativeComponent');
       var ReactReconcileTransaction = require('ReactReconcileTransaction');
 
-      var NodeStub = function(initialProps) {
+      var StubNativeComponent = function(initialProps) {
         ReactComponent.Mixin.construct.call(this, initialProps);
       };
-      mixInto(NodeStub, ReactNativeComponent.Mixin);
+      mixInto(StubNativeComponent, ReactComponent.Mixin);
+      mixInto(StubNativeComponent, ReactNativeComponent.Mixin);
+      mixInto(StubNativeComponent, ReactMultiChild.Mixin);
 
       mountComponent = function(props) {
         var transaction = new ReactReconcileTransaction();
-        return (new NodeStub(props)).mountComponent('test', transaction);
+        var stubComponent = new StubNativeComponent(props);
+        return stubComponent.mountComponent('test', transaction);
       };
     });