diff --git a/huffman.lisp b/huffman.lisp
index 1bda7a5..ff3fea0 100644
--- a/huffman.lisp
+++ b/huffman.lisp
@@ -47,8 +47,8 @@
                   (progn
                     (setq code (+ code 1))
                     (when (> ,codelen-form codelen)
-                      (setq codelen ,codelen-form)
-                      (setq code (ash code 1))))
+                      (setq code (ash code (- ,codelen-form codelen)))
+                      (setq codelen ,codelen-form)))
                   (setq codelen ,codelen-form))
            collect (cons ,key-form (cons code codelen)))))
 ;; (macroexpand '(mkcanon (for pair in sorted-huffman-list while pair) (car pair) (cdr (cdr pair))))