diff --git a/test/flatten-array.js b/test/flatten-array.js
index c7f0632..0660628 100644
--- a/test/flatten-array.js
+++ b/test/flatten-array.js
@@ -1,8 +1,8 @@
 describe('flatten array', function () {
   it('should flatten an array', function () {
-    var arr = [1, 2, [1, 2, [3, 4, 5, [1]]], 2, [2]],
+    let arr = [1, 2, [1, 2, [3, 4, 5, [1]]], 2, [2]],
         expected = [1, 1, 1, 2, 2, 2, 2, 3, 4, 5];
 
     expect(arr).toEqual(expected);
   });
-});
\ No newline at end of file
+});