diff --git a/others/planck.py b/others/planck.py
index edcd64a..af9a59b 100644
--- a/others/planck.py
+++ b/others/planck.py
@@ -33,7 +33,7 @@ ip = 0
 np = 0
 
 def aligned(n):
-    return (n + CELL - 1) & ~(CELL - 1)
+    return (n + CELL - 1) % CELL
 
 def align():
     write(HERE_CELL, aligned(read(HERE_CELL)))