diff --git a/js/src/jsopcode.cpp b/js/src/jsopcode.cpp
index 1c58107abe8b..05da515022f6 100644
--- a/js/src/jsopcode.cpp
+++ b/js/src/jsopcode.cpp
@@ -5489,8 +5489,8 @@ ReconstructPCStack(JSContext *cx, JSScript *script, jsbytecode *target,
         return ReconstructImacroPCStack(cx, script, imacstart, target, pcstack);
 #endif
 
-    LOCAL_ASSERT(script->main <= target && target < script->code + script->length);
-    jsbytecode *pc = script->main;
+    LOCAL_ASSERT(script->code <= target && target < script->code + script->length);
+    jsbytecode *pc = script->code;
     uintN pcdepth = 0;
     ptrdiff_t oplen;
     for (; pc < target; pc += oplen) {
diff --git a/js/src/tests/ecma_5/Global/adding-global-var-nonextensible-error.js b/js/src/tests/ecma_5/Global/adding-global-var-nonextensible-error.js
new file mode 100644
index 000000000000..f4eaf00a293f
--- /dev/null
+++ b/js/src/tests/ecma_5/Global/adding-global-var-nonextensible-error.js
@@ -0,0 +1,35 @@
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 621432;
+var summary =
+  "If a var statement can't create a global property because the global " +
+  "object isn't extensible, and an error is thrown while decompiling the " +
+  "global, don't assert";
+
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+var toSource = [];
+Object.preventExtensions(this);
+
+try
+{
+  eval("var x;");
+  throw new Error("no error thrown");
+}
+catch (e)
+{
+  assertEq(e instanceof TypeError, true, "expected TypeError, got: " + e);
+}
+
+/******************************************************************************/
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("All tests passed!");
diff --git a/js/src/tests/ecma_5/Global/jstests.list b/js/src/tests/ecma_5/Global/jstests.list
index 1da36470ae4b..5976eb0a6f99 100644
--- a/js/src/tests/ecma_5/Global/jstests.list
+++ b/js/src/tests/ecma_5/Global/jstests.list
@@ -1,4 +1,5 @@
 url-prefix ../../jsreftest.html?test=ecma_5/Global/
+script adding-global-var-nonextensible-error.js
 script parseInt-01.js
 script parseFloat-01.js
 script eval-01.js