diff --git a/test/built-ins/Array/prototype/flatMap/thisArg-argument.js b/test/built-ins/Array/prototype/flatMap/thisArg-argument.js
index a2217e6fb8..f53821614e 100644
--- a/test/built-ins/Array/prototype/flatMap/thisArg-argument.js
+++ b/test/built-ins/Array/prototype/flatMap/thisArg-argument.js
@@ -6,10 +6,9 @@ description: >
     Behavior when thisArg is provided
     Array.prototype.flatMap ( mapperFunction [ , thisArg ] )
 includes: [compareArray.js]
+flags: [onlyStrict]
 ---*/
 
-"use strict";
-
 var a = {};
 
 assert(compareArray([1].flatMap(function() { return [this]; }, "TestString"), ["TestString"]));