(define %poll-sockets
  (foreign-safe-lambda* int
                        ((scheme-object poll_item_ref)
                         (unsigned-int length)
                         (long timeout))
                        "zmq_pollitem_t items[length];
                         zmq_pollitem_t *item_ptrs[length];
                         int i;

                         for (i = 0; i < length; i++) {
                           C_save(C_fix(i));
                           item_ptrs[i] = (zmq_pollitem_t *)C_pointer_address(C_callback(poll_item_ref, 1));
                         }

                         for (i = 0; i < length; i++) {
                           items[i] = *item_ptrs[i];
                         }

                         int rc = zmq_poll(items, length, timeout);

                         if (rc != -1) {
                           for (i = 0; i < length; i++) {
                             (*item_ptrs[i]).revents = items[i].revents;
                           }
                         }

                         C_return(rc);"))

(define (poll poll-items timeout/block)
  (if (null? poll-items)
      (error 'poll "null list passed for poll-items")
      (let ((result (%poll-sockets (lambda (i) 
                                     (poll-item-pointer (list-ref poll-items i))) ;; <---- HERE it is
                                   (length poll-items)
                                   (case timeout/block
                                     ((#f) 0)
                                     ((#t) -1)
                                     (else timeout/block)))))
        (if (= result -1)
            (zmq-error 'poll)
            result))))