add function problem

could someone tell me why this peace of bro-code makes a segmentation fault?

-------------------------------------------------

global sessions : set[conn_id];

event ftp_request(c:connection, command: string, arg:string)
{
  add sessions[c$id];
}

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Ouch, I don't know why that's happening, but I've added it to the
to-fix list.

But the more basic problem is that "add" is not currently supported.
You need to instead use:

  global sessions: table[conn_id] of bool;

  event ftp_request(c:connection, command: string, arg:string)
    {
    sessions[c$id] = T;
    }

- Vern