diff -r 000000000000 -r 6474c204b198 js/src/tests/test262/ch11/11.4/11.4.7/S11.4.7_A4.1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/test262/ch11/11.4/11.4.7/S11.4.7_A4.1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,21 @@
+// Copyright 2009 the Sputnik authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/**
+ * If x is NaN, operator -x returns NaN
+ *
+ * @path ch11/11.4/11.4.7/S11.4.7_A4.1.js
+ * @description Checking NaN
+ */
+
+//CHECK#1
+if (isNaN(-NaN) !== true) {
+  $ERROR('#1: -NaN === Not-a-Number. Actual: ' + (-NaN));
+}
+
+//CHECK#2
+var x = NaN; 
+if (isNaN(-x) != true) {
+  $ERROR('#2: var x = NaN; -x === Not-a-Number. Actual: ' + (-x));
+}
+