diff --git a/src/pocketmine/inventory/CraftingManager.php b/src/pocketmine/inventory/CraftingManager.php
index b4b1e7a80..4d869c960 100644
--- a/src/pocketmine/inventory/CraftingManager.php
+++ b/src/pocketmine/inventory/CraftingManager.php
@@ -235,7 +235,7 @@ class CraftingManager{
 		/** @var Item[] $row */
 		foreach($map as $y => $row){
 			foreach($row as $x => $item){
-				$item = clone $item;
+				$map[$y][$x] = clone $item;
 			}
 		}