diff --git a/packages/react-dom/src/client/ReactDOM.js b/packages/react-dom/src/client/ReactDOM.js
index aaf429cad5..04355605ed 100644
--- a/packages/react-dom/src/client/ReactDOM.js
+++ b/packages/react-dom/src/client/ReactDOM.js
@@ -107,7 +107,7 @@ setBatchingImplementation(
 
 function createPortal(
   children: ReactNodeList,
-  container: Container,
+  container: Element | DocumentFragment,
   key: ?string = null,
 ): React$Portal {
   if (!isValidContainer(container)) {