diff --git a/src/ChestShop/EventListener.php b/src/ChestShop/EventListener.php
index 46d00c6..fc205e8 100644
--- a/src/ChestShop/EventListener.php
+++ b/src/ChestShop/EventListener.php
@@ -11,7 +11,6 @@
 use pocketmine\level\Position;
 use pocketmine\math\Vector3;
 use pocketmine\tile\Chest as TileChest;
-use pocketmine\block\Chest as BlockChest;
 
 class EventListener implements Listener
 {
@@ -55,7 +54,7 @@ public function onPlayerInteract(PlayerInteractEvent $event)
                 $itemNum = 0;
                 $pID = $shopInfo['productID'];
                 $pMeta = $shopInfo['productMeta'];
-                for ($i = 0; $i < BlockChest::SLOTS; $i++) {
+                for ($i = 0; $i < $chest->getSize(); $i++) {
                     $item = $chest->getInventory()->getItem($i);
                     // use getDamage() method to get metadata of item
                     if ($item->getID() === $pID and $item->getDamage() === $pMeta) $itemNum += $item->getCount();
@@ -72,7 +71,7 @@ public function onPlayerInteract(PlayerInteractEvent $event)
                 $player->getInventory()->addItem(clone Item::get((int)$shopInfo['productID'], (int)$shopInfo['productMeta'], (int)$shopInfo['saleNum']));
 
                 $tmpNum = $shopInfo['saleNum'];
-                for ($i = 0; $i < BlockChest::SLOTS; $i++) {
+                for ($i = 0; $i < $chest->getSize(); $i++) {
                     $item = $chest->getInventory()->getItem($i);
                     // Use getDamage() method to get metadata of item
                     if ($item->getID() === $pID and $item->getDamage() === $pMeta) {