diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/parallel/write-illegal-array-elt.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/parallel/write-illegal-array-elt.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,17 @@
+load(libdir + "parallelarray-helpers.js");
+
+function testMap() {
+  var p = range(0, minItemsTestingThreshold);
+  var v = [1];
+  var func = function (e) {
+    v[0] = e;
+    return 0;
+  };
+
+  // this will compile, but fail at runtime
+  assertParallelExecWillBail(m => p.mapPar(func, m));
+}
+
+if (getBuildConfiguration().parallelJS)
+  testMap();
+