diff --git a/react/react-addons-test-utils.d.ts b/react/react-addons-test-utils.d.ts
index 0c29507a0..efe8392a1 100644
--- a/react/react-addons-test-utils.d.ts
+++ b/react/react-addons-test-utils.d.ts
@@ -104,10 +104,17 @@ declare namespace __React {
             export function mockComponent(
                 mocked: MockedComponentClass, mockTagName?: string): typeof TestUtils;
 
-            export function isElementOfType(
-                element: ReactElement<any>, type: ReactType): boolean;
-            export function isDOMComponent(instance: ReactInstance): boolean;
-            export function isCompositeComponent(instance: ReactInstance): boolean;
+            export function isElementOfType<T extends HTMLElement>(
+                element: ReactElement<any>, type: string): element is ReactHTMLElement<T>;
+            export function isElementOfType<P extends DOMAttributes, T extends Element>(
+                element: ReactElement<any>, type: string): element is DOMElement<P, T>;
+            export function isElementOfType<P>(
+                element: ReactElement<any>, type: SFC<P>): element is SFCElement<P>;
+            export function isElementOfType<P, T extends Component<P, {}>, C extends ComponentClass<P>>(
+                element: ReactElement<any>, type: ClassType<P, T, C>): element is CElement<P, T>;
+
+            export function isDOMComponent(instance: ReactInstance): instance is Element;
+            export function isCompositeComponent(instance: ReactInstance): instance is Component<any, any>;
             export function isCompositeComponentWithType(
                 instance: ReactInstance,
                 type: ComponentClass<any>): boolean;
diff --git a/react/react-tests.ts b/react/react-tests.ts
index 9a3ac5f50..aa485b2ae 100644
--- a/react/react-tests.ts
+++ b/react/react-tests.ts
@@ -220,9 +220,12 @@ domNode = ReactDOM.findDOMNode(domNode);
 // React Elements
 // --------------------------------------------------------------------------
 
-var type = element.type;
+var type: React.ComponentClass<Props> = element.type;
 var elementProps: Props = element.props;
-var key = element.key;
+var key: React.Key = element.key;
+
+var t: React.ReactType<any>;
+var name = typeof t === "string" ? t : t.displayName;
 
 //
 // React Components
@@ -543,6 +546,20 @@ var foundComponent: ModernComponent = TestUtils.findRenderedComponentWithType(
 var foundComponents: ModernComponent[] = TestUtils.scryRenderedComponentsWithType(
     inst, ModernComponent);
 
+// ReactTestUtils custom type guards
+
+var emptyElement: React.ReactElement<{}>;
+if (TestUtils.isElementOfType(emptyElement, StatelessComponent)) {
+    emptyElement.props.foo;
+}
+
+var anyInstance: Element | React.Component<any, any>;
+if (TestUtils.isDOMComponent(anyInstance)) {
+    anyInstance.getAttribute("className");
+} else if (TestUtils.isCompositeComponent(anyInstance)) {
+    anyInstance.props;
+}
+
 //
 // TransitionGroup addon
 // --------------------------------------------------------------------------
diff --git a/react/react.d.ts b/react/react.d.ts
index 927a06ffa..c06081019 100644
--- a/react/react.d.ts
+++ b/react/react.d.ts
@@ -174,12 +174,12 @@ declare namespace __React {
         contextTypes?: ValidationMap<any>;
         childContextTypes?: ValidationMap<any>;
         defaultProps?: P;
+        displayName?: string;
     }
 
     interface ClassicComponentClass<P> extends ComponentClass<P> {
         new(props?: P, context?: any): ClassicComponent<P, any>;
         getDefaultProps?(): P;
-        displayName?: string;
     }
 
     //