gnu indent: where are the tabs?

I've just started looking into gnu indent and I'm having some trouble
making it format the source code using tabs. In the man pages it is said
that the -ut and -ts options could handle that but no matter how I run
indent, the source code still appears exactly like if it was run with
indent --no-tabs.

The result is as following:

int test(int param)
{
  if (param == 1))
    {
      printf ("error\n");
      return EXIT_SUCCESS;
    }
  return EXIT_SUCCESS;
}

Is gnu indent broken? What do I need to do to be able to format the
code with leading tabs? Something like:

int test(int param)
{
        if (param == 1))
        {
                printf ("error\n");
                return EXIT_SUCCESS;
        }
        return EXIT_SUCCESS;
}