diff --git a/src/App.js b/src/App.js
index 3a3d194e7..e84d1ae85 100644
--- a/src/App.js
+++ b/src/App.js
@@ -8,7 +8,7 @@
 import React from 'react';
 import {FlexColumn, FlexRow} from 'flipper';
 import {connect} from 'react-redux';
-import WelcomeScreen from './chrome/WelcomeScreen.js';
+import WelcomeScreen from './chrome/WelcomeScreen.tsx';
 // $FlowFixMe T47375728
 import TitleBar from './chrome/TitleBar.tsx';
 import MainSidebar from './chrome/MainSidebar.js';
diff --git a/src/chrome/WelcomeScreen.js b/src/chrome/WelcomeScreen.tsx
similarity index 98%
rename from src/chrome/WelcomeScreen.js
rename to src/chrome/WelcomeScreen.tsx
index 29609b6db..1ad51fefe 100644
--- a/src/chrome/WelcomeScreen.js
+++ b/src/chrome/WelcomeScreen.tsx
@@ -7,7 +7,6 @@
 
 import {
   styled,
-  PureComponent,
   FlexColumn,
   FlexRow,
   Text,
@@ -17,6 +16,7 @@ import {
 } from 'flipper';
 import isProduction from '../utils/isProduction.js';
 import {shell, remote} from 'electron';
+import React, {PureComponent} from 'react';
 
 const Container = styled(FlexColumn)({
   height: '100%',
@@ -98,7 +98,7 @@ export default class WelcomeScreen extends PureComponent<Props, State> {
     isMounted: false,
   };
 
-  timer: ?TimeoutID;
+  timer: NodeJS.Timeout | null | undefined;
 
   componentDidMount() {
     // waiting sometime before showing the welcome screen to allow Flipper to