ordered words problem common lisp

(defun string-to-list (str)
  (loop for char across str
     collect char))

(defun ordered-word-p (str)
  (if (= 0 (length str))
      nil
      (apply #'CHAR-NOT-GREATERP (string-to-list str))))

(defun words ()
  (with-open-file (in "/usr/share/dict/words")
    (loop for line = (read-line in nil)
       while line collect line)))

(defun ordered-words (words)
  (remove-if-not #'ordered-word-p words))

(defun longest-ordered-words (words)
  (let ((ow (ordered-words words))
    (longest (list))
    (longest-length 0))
    (loop
       for w in ow
       for cur-length = (length w)
       ;;add to list of longest words
       when (= cur-length longest-length) do
     (setf longest (cons w longest))
       ;;replace list of longest words
       when (> cur-length longest-length) do
     (progn
       (setf longest-length cur-length)
       (setf longest (list w)))
       finally (return (reverse longest)))))