diff --git a/src/pocketmine/block/BurningFurnace.php b/src/pocketmine/block/BurningFurnace.php
index 72f3453e1..01bbd6779 100644
--- a/src/pocketmine/block/BurningFurnace.php
+++ b/src/pocketmine/block/BurningFurnace.php
@@ -26,7 +26,6 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\item\TieredTool;
 use pocketmine\math\Vector3;
-use pocketmine\nbt\tag\StringTag;
 use pocketmine\Player;
 use pocketmine\tile\Furnace as TileFurnace;
 use pocketmine\tile\Tile;
@@ -83,7 +82,7 @@ class BurningFurnace extends Solid{
 				$furnace = Tile::createTile(Tile::FURNACE, $this->getLevel(), TileFurnace::createNBT($this));
 			}
 
-			if($furnace->namedtag->hasTag("Lock", StringTag::class) and $furnace->namedtag->getString("Lock") !== $item->getCustomName()){
+			if(!$furnace->canOpenWith($item->getCustomName())){
 				return true;
 			}
 
diff --git a/src/pocketmine/block/Chest.php b/src/pocketmine/block/Chest.php
index edd1077ae..b11809ef2 100644
--- a/src/pocketmine/block/Chest.php
+++ b/src/pocketmine/block/Chest.php
@@ -26,7 +26,6 @@ namespace pocketmine\block;
 use pocketmine\item\Item;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Vector3;
-use pocketmine\nbt\tag\StringTag;
 use pocketmine\Player;
 use pocketmine\tile\Chest as TileChest;
 use pocketmine\tile\Tile;
@@ -115,7 +114,7 @@ class Chest extends Transparent{
 			if(
 				!$this->getSide(Vector3::SIDE_UP)->isTransparent() or
 				($chest->isPaired() and !$chest->getPair()->getBlock()->getSide(Vector3::SIDE_UP)->isTransparent()) or
-				($chest->namedtag->hasTag("Lock", StringTag::class) and $chest->namedtag->getString("Lock") !== $item->getCustomName())
+				!$chest->canOpenWith($item->getCustomName())
 			){
 				return true;
 			}
diff --git a/src/pocketmine/tile/Container.php b/src/pocketmine/tile/Container.php
index b88c340c5..1e98dc5a1 100644
--- a/src/pocketmine/tile/Container.php
+++ b/src/pocketmine/tile/Container.php
@@ -27,6 +27,7 @@ use pocketmine\inventory\Inventory;
 
 interface Container{
 	public const TAG_ITEMS = "Items";
+	public const TAG_LOCK = "Lock";
 
 	/**
 	 * @return Inventory
@@ -37,4 +38,13 @@ interface Container{
 	 * @return Inventory
 	 */
 	public function getRealInventory();
+
+	/**
+	 * Returns whether this container can be opened by an item with the given custom name.
+	 *
+	 * @param string $key
+	 *
+	 * @return bool
+	 */
+	public function canOpenWith(string $key) : bool;
 }
diff --git a/src/pocketmine/tile/ContainerTrait.php b/src/pocketmine/tile/ContainerTrait.php
index 7cdc6f5f0..10501c9cc 100644
--- a/src/pocketmine/tile/ContainerTrait.php
+++ b/src/pocketmine/tile/ContainerTrait.php
@@ -28,11 +28,14 @@ use pocketmine\item\Item;
 use pocketmine\nbt\NBT;
 use pocketmine\nbt\tag\CompoundTag;
 use pocketmine\nbt\tag\ListTag;
+use pocketmine\nbt\tag\StringTag;
 
 /**
  * This trait implements most methods in the {@link Container} interface. It should only be used by Tiles.
  */
 trait ContainerTrait{
+	/** @var string|null */
+	private $lock;
 
 	abstract public function getNBT() : CompoundTag;
 
@@ -51,6 +54,10 @@ trait ContainerTrait{
 				$inventory->setItem($itemNBT->getByte("Slot"), Item::nbtDeserialize($itemNBT));
 			}
 		}
+
+		if($this->getNBT()->hasTag(Container::TAG_LOCK, StringTag::class)){
+			$this->lock = $this->getNBT()->getString(Container::TAG_LOCK);
+		}
 	}
 
 	protected function saveItems() : void{
@@ -60,5 +67,20 @@ trait ContainerTrait{
 		}
 
 		$this->getNBT()->setTag(new ListTag(Container::TAG_ITEMS, $items, NBT::TAG_Compound));
+
+		if($this->lock !== null){
+			$this->getNBT()->setString(Container::TAG_LOCK, $this->lock);
+		}
+	}
+
+	/**
+	 * @see Container::canOpenWith()
+	 *
+	 * @param string $key
+	 *
+	 * @return bool
+	 */
+	public function canOpenWith(string $key) : bool{
+		return $this->lock === null or $this->lock === $key;
 	}
 }