diff --git a/src/Portal.js b/src/Portal.js
index cb832ebd..fb98e3e7 100644
--- a/src/Portal.js
+++ b/src/Portal.js
@@ -30,7 +30,7 @@ class Portal extends React.Component {
     onRendered: PropTypes.func,
   };
 
-  componentWillMount() {
+  UNSAFE_componentWillMount() {
     if (!canUseDom) {
       return;
     }