diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/parallel/write-illegal-obj.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/parallel/write-illegal-obj.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,19 @@
+load(libdir + "parallelarray-helpers.js");
+
+function buildSimple() {
+
+  let obj = { x: 1, y: 2, z: 3 };
+
+  assertParallelExecWillBail(function(m) {
+    Array.buildPar(minItemsTestingThreshold, function(i) {
+        obj.x += 1;
+        obj.y += 1;
+        obj.z += 1;
+        return obj;
+    }, m);
+  });
+
+}
+
+if (getBuildConfiguration().parallelJS)
+  buildSimple();