diff --git a/src/day5.ml b/src/day5.ml
index 333d7c2..e0ea2d4 100644
--- a/src/day5.ml
+++ b/src/day5.ml
@@ -1,14 +1,11 @@
 open Containers
 
-let crane_drop stacks index box =
-  let stack = Array.get stacks index in
-  Array.set stacks index (box @ stack)
-;;
+let crane_drop stacks index boxes = stacks.(index) <- boxes @ stacks.(index)
 
 let crane_lift stacks index count =
-  let stack = Array.get stacks index in
+  let stack = stacks.(index) in
   let boxes, rest = List.take_drop count stack in
-  Array.set stacks index rest;
+  stacks.(index) <- rest;
   boxes
 ;;