diff --git a/types/react-dom/index.d.ts b/types/react-dom/index.d.ts
index bd9541217d..e7a5afe59d 100644
--- a/types/react-dom/index.d.ts
+++ b/types/react-dom/index.d.ts
@@ -19,7 +19,7 @@ import {
 export function findDOMNode(instance: ReactInstance): Element | null | Text;
 export function unmountComponentAtNode(container: Element): boolean;
 
-export function createPortal(children: ReactNode, container: Element): ReactPortal;
+export function createPortal(children: ReactNode, container: Element, key?: null | string): ReactPortal;
 
 export const version: string;
 export const render: Renderer;
diff --git a/types/react-dom/react-dom-tests.tsx b/types/react-dom/react-dom-tests.tsx
index 3f153b0a75..ff5ef5850e 100644
--- a/types/react-dom/react-dom-tests.tsx
+++ b/types/react-dom/react-dom-tests.tsx
@@ -42,7 +42,14 @@ describe('ReactDOM', () => {
             }
         }
 
-        ReactDOM.createPortal(React.createElement('div'), portalTarget);
+        ReactDOM.createPortal(<div />, document.createElement('div'));
+        ReactDOM.createPortal(<div />, document.createElement('div'), null);
+        ReactDOM.createPortal(<div />, document.createElement('div'), 'key');
+
+        ReactDOM.createPortal(React.createElement('div'), document.createElement('div'));
+        ReactDOM.createPortal(React.createElement('div'), document.createElement('div'), null);
+        ReactDOM.createPortal(React.createElement('div'), document.createElement('div'), 'key');
+
         ReactDOM.render(<ClassComponent />, rootElement);
     });
 });