--- a/js/src/tests/ecma_6/Math/shell.js
+++ b/js/src/tests/ecma_6/Math/shell.js
@@ -1,14 +1,14 @@
 // The nearest representable values to +1.0.
 const ONE_PLUS_EPSILON = 1 + Math.pow(2, -52);  // 0.9999999999999999
 const ONE_MINUS_EPSILON = 1 - Math.pow(2, -53);  // 1.0000000000000002
 
 {
-    var fail = function (msg) {
+    const fail = function (msg) {
         var exc = new Error(msg);
         try {
             // Try to improve on exc.fileName and .lineNumber; leave exc.stack
             // alone. We skip two frames: fail() and its caller, an assertX()
             // function.
             var frames = exc.stack.trim().split("\n");
             if (frames.length > 2) {
                 var m = /@([^@:]*):([0-9]+)$/.exec(frames[2]);
@@ -16,31 +16,31 @@ const ONE_MINUS_EPSILON = 1 - Math.pow(2
                     exc.fileName = m[1];
                     exc.lineNumber = +m[2];
                 }
             }
         } catch (ignore) { throw ignore;}
         throw exc;
     };
 
-    var ENDIAN;  // 0 for little-endian, 1 for big-endian.
+    let ENDIAN;  // 0 for little-endian, 1 for big-endian.
 
     // Return the difference between the IEEE 754 bit-patterns for a and b.
     //
     // This is meaningful when a and b are both finite and have the same
     // sign. Then the following hold:
     //
     //   * If a === b, then diff(a, b) === 0.
     //
     //   * If a !== b, then diff(a, b) === 1 + the number of representable values
     //                                         between a and b.
     //
-    var f = new Float64Array([0, 0]);
-    var u = new Uint32Array(f.buffer);
-    var diff = function (a, b) {
+    const f = new Float64Array([0, 0]);
+    const u = new Uint32Array(f.buffer);
+    const diff = function (a, b) {
         f[0] = a;
         f[1] = b;
         //print(u[1].toString(16) + u[0].toString(16) + " " + u[3].toString(16) + u[2].toString(16));
         return Math.abs((u[3-ENDIAN] - u[1-ENDIAN]) * 0x100000000 + u[2+ENDIAN] - u[0+ENDIAN]);
     };
 
     // Set ENDIAN to the platform's endianness.
     ENDIAN = 0;  // try little-endian first