diff --git a/Libraries/vendor/core/merge.js b/Libraries/vendor/core/merge.js
index a294d4af6d9..dea7716a282 100644
--- a/Libraries/vendor/core/merge.js
+++ b/Libraries/vendor/core/merge.js
@@ -3,9 +3,12 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ * @format
  */
 
-"use strict";
+'use strict';
 
 const mergeInto = require('./mergeInto');
 
@@ -16,10 +19,11 @@ const mergeInto = require('./mergeInto');
  * @param {?object} two Optional object with properties to merge from.
  * @return {object} The shallow extension of one by two.
  */
-const merge = function(one, two) {
+const merge = function<T1, T2>(one: T1, two: T2): {...T1, ...T2} {
   const result = {};
   mergeInto(result, one);
   mergeInto(result, two);
+  // $FlowFixMe mergeInto is not typed
   return result;
 };