diff --git a/src/utils/__tests__/promiseTimeout.node.js b/src/utils/__tests__/promiseTimeout.node.js
index 777ed0fae..c3bf3785c 100644
--- a/src/utils/__tests__/promiseTimeout.node.js
+++ b/src/utils/__tests__/promiseTimeout.node.js
@@ -4,7 +4,7 @@
  * LICENSE file in the root directory of this source tree.
  * @format
  */
-import promiseTimeout from '../promiseTimeout';
+import promiseTimeout from '../promiseTimeout.tsx';
 
 test('test promiseTimeout for timeout to happen', () => {
   const promise = promiseTimeout(
diff --git a/src/utils/exportData.js b/src/utils/exportData.js
index 7918d69d2..9a335563d 100644
--- a/src/utils/exportData.js
+++ b/src/utils/exportData.js
@@ -23,7 +23,7 @@ import {serialize, deserialize} from './serialization';
 import {readCurrentRevision} from './packageMetadata.js';
 import {tryCatchReportPlatformFailures} from './metrics';
 import {promisify} from 'util';
-import promiseTimeout from './promiseTimeout';
+import promiseTimeout from './promiseTimeout.tsx';
 import {Idler} from './Idler';
 export const IMPORT_FLIPPER_TRACE_EVENT = 'import-flipper-trace';
 export const EXPORT_FLIPPER_TRACE_EVENT = 'export-flipper-trace';
diff --git a/src/utils/promiseTimeout.js b/src/utils/promiseTimeout.tsx
similarity index 83%
rename from src/utils/promiseTimeout.js
rename to src/utils/promiseTimeout.tsx
index 0f8c4ba63..8497d72a2 100644
--- a/src/utils/promiseTimeout.js
+++ b/src/utils/promiseTimeout.tsx
@@ -8,10 +8,10 @@
 export default function promiseTimeout<T>(
   ms: number,
   promise: Promise<T>,
-  timeoutMessage: ?string,
-): Promise<T> | Promise<void> {
+  timeoutMessage?: string,
+): Promise<T> {
   // Create a promise that rejects in <ms> milliseconds
-  const timeout = new Promise((resolve, reject) => {
+  const timeout: Promise<T> = new Promise((resolve, reject) => {
     const id = setTimeout(() => {
       clearTimeout(id);
       reject(new Error(timeoutMessage || `Timed out in ${ms} ms.`));