diff --git a/distances.lisp b/distances.lisp
index 60a5e25..0d1c37a 100644
--- a/distances.lisp
+++ b/distances.lisp
@@ -37,12 +37,13 @@
   (let* ((frontier (list (root-cell d)))
          (new-frontier ()))
     (loop while (not (null frontier)) 
-      do (dolist (cell frontier)
-        (setf new-frontier ())
-        (dolist (linked (links cell))
-          (when (not (gethash linked (distance-cells d)))
-            (set-distance d :cell linked :distance (+ 1 (gethash cell (distance-cells d))))
-            (setf new-frontier (append `(,linked) new-frontier)))))
+      do 
+         (setf new-frontier ())
+         (dolist (cell frontier)
+           (dolist (linked (links cell))
+             (when (not (gethash linked (distance-cells d)))
+               (set-distance d :cell linked :distance (+ 1 (gethash cell (distance-cells d))))
+               (setf new-frontier (append `(,linked) new-frontier)))))
          (setf frontier (copy-tree new-frontier))))
   (distance-cells d))