1 files changed, 15 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/testUndefinedIncrement.js b/js/src/jit-test/tests/basic/testUndefinedIncrement.js
new file mode 100644
index 0000000000..a42557b3b7
--- /dev/null
+++ b/js/src/jit-test/tests/basic/testUndefinedIncrement.js
@@ -0,0 +1,15 @@
+function f() {
+    var n;
+    var k;
+    for (var i = 0; i < 18; ++i) {
+	n = undefined;
+	k = n++;
+	if (k) { }
+    }
+    return [k, n];
+}
+
+var [a, b] = f();
+
+assertEq(isNaN(a), true);
+assertEq(isNaN(b), true);