--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -1935,26 +1935,31 @@ nsJSContext::ExecuteScript(void *aScript
   }
 
   // The result of evaluation, used only if there were no errors.  This need
   // not be a GC root currently, provided we run the GC only from the
   // operation callback or from ScriptEvaluated.
   jsval val;
   JSBool ok;
 
+  JSObject *scriptObj = (JSObject*)aScriptObject;
+  nsCOMPtr<nsIPrincipal> principal;
+
+  rv = sSecurityManager->GetObjectPrincipal(mContext, scriptObj, getter_AddRefs(principal));
+  NS_ENSURE_SUCCESS(rv, rv);
+
   rv = sSecurityManager->PushContextPrincipal(mContext, nsnull, principal);
   NS_ENSURE_SUCCESS(rv, rv);
 
   nsJSContext::TerminationFuncHolder holder(this);
   JSAutoRequest ar(mContext);
   ++mExecuteDepth;
   ok = ::JS_ExecuteScript(mContext,
                           (JSObject *)aScopeObject,
-                          (JSScript*)::JS_GetPrivate(mContext,
-                          (JSObject*)aScriptObject),
+                          (JSScript*)::JS_GetPrivate(mContext, scriptObj),
                           &val);
 
   if (ok) {
     // If all went well, convert val to a string (XXXbe unless undefined?).
     rv = JSValueToAString(mContext, val, aRetValue, aIsUndefined);
   } else {
     if (aIsUndefined) {
       *aIsUndefined = PR_TRUE;