diff --git a/src/pocketmine/inventory/CraftingManager.php b/src/pocketmine/inventory/CraftingManager.php
index a1818ffe6..b5675b64a 100644
--- a/src/pocketmine/inventory/CraftingManager.php
+++ b/src/pocketmine/inventory/CraftingManager.php
@@ -321,7 +321,7 @@ class CraftingManager{
 	public function matchFurnaceRecipe(Item $input){
 		if(isset($this->furnaceRecipes[$input->getID() . ":" . $input->getDamage()])){
 			return $this->furnaceRecipes[$input->getID() . ":" . $input->getDamage()];
-		}elseif($this->furnaceRecipes[$input->getID() . ":?"]){
+		}elseif(isset($this->furnaceRecipes[$input->getID() . ":?"])){
 			return $this->furnaceRecipes[$input->getID() . ":?"];
 		}