diff --git a/js/src/tests/ecma_5/extensions/jstests.list b/js/src/tests/ecma_5/extensions/jstests.list
index 427cfea606b9..962f4ee99078 100644
--- a/js/src/tests/ecma_5/extensions/jstests.list
+++ b/js/src/tests/ecma_5/extensions/jstests.list
@@ -22,6 +22,7 @@ script strict-function-statements.js
 script strict-option-redeclared-parameter.js
 script string-literal-getter-setter-decompilation.js
 script uneval-strict-functions.js
+script watch-array-length.js
 script watch-inherited-property.js
 script watch-replaced-setter.js
 script watch-setter-become-setter.js
diff --git a/js/src/tests/ecma_5/extensions/watch-array-length.js b/js/src/tests/ecma_5/extensions/watch-array-length.js
new file mode 100644
index 000000000000..e9b356efa514
--- /dev/null
+++ b/js/src/tests/ecma_5/extensions/watch-array-length.js
@@ -0,0 +1,41 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+var hitCount;
+function watcher(p,o,n) { hitCount++; return n; }
+
+var a = [1];
+a.watch('length', watcher);
+hitCount = 0;
+a.length = 0;
+reportCompare(1, hitCount, "lenient; configurable: watchpoint hit");
+
+var b = Object.defineProperty([1],'0',{configurable:false});
+b.watch('length', watcher);
+hitCount = 0;
+var result;
+try {
+    b.length = 0;    
+    result = "no error";
+} catch (x) {
+    result = x.toString();
+}
+reportCompare(1, hitCount, "lenient; non-configurable: watchpoint hit");
+reportCompare(1, b.length, "lenient; non-configurable: length unchanged");
+reportCompare("no error", result, "lenient; non-configurable: no error thrown");
+
+var c = Object.defineProperty([1],'0',{configurable:false});
+c.watch('length', watcher);
+hitCount = 0;
+var threwTypeError;
+try {
+    (function(){'use strict'; c.length = 0;})();
+    threwTypeError = false;
+} catch (x) {
+    threwTypeError = x instanceof TypeError;
+}
+reportCompare(1, hitCount, "strict; non-configurable: watchpoint hit");
+reportCompare(1, c.length, "strict; non-configurable: length unchanged");
+reportCompare(true, threwTypeError, "strict; non-configurable: TypeError thrown");
diff --git a/js/src/tests/ecma_5/strict/jstests.list b/js/src/tests/ecma_5/strict/jstests.list
index 114265f807e7..5049b8a77ee7 100644
--- a/js/src/tests/ecma_5/strict/jstests.list
+++ b/js/src/tests/ecma_5/strict/jstests.list
@@ -25,7 +25,7 @@ script 15.4.4.8.js
 script 15.4.4.9.js
 script 15.4.4.12.js
 script 15.4.4.13.js
-skip script 15.4.5.1.js  # Waiting for bug 537873 to be fully resolved.
+script 15.4.5.1.js
 script 15.5.5.1.js
 script 15.5.5.2.js
 script 15.10.7.js
@@ -35,6 +35,7 @@ script function-name-arity.js
 script primitive-this-no-writeback.js
 script regress-532254.js
 script regress-532041.js
+script regress-599159.js
 script unbrand-this.js
 script this-for-function-expression-recursion.js
 script assign-to-callee-name.js
diff --git a/js/src/tests/ecma_5/strict/regress-599159.js b/js/src/tests/ecma_5/strict/regress-599159.js
new file mode 100644
index 000000000000..c29b0ebdc154
--- /dev/null
+++ b/js/src/tests/ecma_5/strict/regress-599159.js
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+// Shu's test
+function test(makeNonArray) {
+    function C() {}
+    C.prototype = []
+    if (makeNonArray)
+        C.prototype.constructor = C
+    c = new C();
+    c.push("foo");
+    return c.length
+}
+assertEq(test(true), 1);
+assertEq(test(false), 1);
+
+// jorendorff's longer test
+var a = [];
+a.slowify = 1;
+var b = Object.create(a);
+b.length = 12;
+assertEq(b.length, 12);
+
+// jorendorff's shorter test
+var b = Object.create(Array.prototype);
+b.length = 12;
+assertEq(b.length, 12);
+
+reportCompare(true, true);