diff --git a/p1/p1.org b/p1/p1.org
index b884e07..66e74b9 100644
--- a/p1/p1.org
+++ b/p1/p1.org
@@ -35,7 +35,7 @@ For part 2, This works:
   (defun average (li)
     (/ (-sum li) (length li)))
 
-  (let ((number-lists (--map (-running-sum (append (list it) data))
+  (let ((number-lists (--map (-running-sum (cons it data))
   			   (list 50.5 49.5))))
     (average (--map 
   	    (-sum (--map (abs (- (car it) (cdr it)))