diff --git a/src/pocketmine/inventory/BaseInventory.php b/src/pocketmine/inventory/BaseInventory.php
index 33e5b5f960..e36dfbdd7b 100644
--- a/src/pocketmine/inventory/BaseInventory.php
+++ b/src/pocketmine/inventory/BaseInventory.php
@@ -330,6 +330,11 @@ abstract class BaseInventory implements Inventory{
 		}
 	}
 
+	/**
+	 * @param Player $source
+	 *
+	 * @return Player[]
+	 */
 	public function getViewers($source = null){
 		$viewers = [];
 		foreach($this->viewers as $viewer){
diff --git a/src/pocketmine/inventory/FurnaceInventory.php b/src/pocketmine/inventory/FurnaceInventory.php
index a2ee762ffd..91d322f56e 100644
--- a/src/pocketmine/inventory/FurnaceInventory.php
+++ b/src/pocketmine/inventory/FurnaceInventory.php
@@ -87,6 +87,7 @@ class FurnaceInventory extends ContainerInventory{
 
 	public function onSlotChange($index, $before, $source = null){
 		parent::onSlotChange($index, $before, $source);
-		//TODO: implement Furnace scheduled update
+
+		$this->getHolder()->scheduleUpdate();
 	}
 }