can't step into for each loop in Firefox Debugger

can't step into for each loop in Firefox Debugger

I'm trying to do an $.each on a json object, but when debugging in Firefox it's just steps over this code, like something goes wrong.

Code:
  1. var query = { name: "test" };
  2. $.each(query, function (k, v) {
  3.     if (i === 1) {
  4.         tmp = "?";
  5.     }
  6.     else {
  7.         tmp += "&";
  8.     }
  9.     tmp += k + "=" + v;
  10.     i++;
  11. });

Am I using $.each wrong?