diff --git a/src/main/kotlin/io/delilaheve/util/ItemUtil.kt b/src/main/kotlin/io/delilaheve/util/ItemUtil.kt
index b883f3e9..e0cd2c3b 100644
--- a/src/main/kotlin/io/delilaheve/util/ItemUtil.kt
+++ b/src/main/kotlin/io/delilaheve/util/ItemUtil.kt
@@ -82,6 +82,6 @@ object ItemUtil {
      * The two items should either be the same type, or, the [other] is a book
      */
     fun ItemStack.canMergeWith(
-        other: ItemStack?
-    ) = (other != null) && (customType == other.customType || (other.isEnchantedBook()))
+        other: ItemStack
+    ) = customType == other.customType || (other.isEnchantedBook())
 }
diff --git a/src/main/kotlin/xyz/alexcrea/cuanvil/listener/AnvilResultListener.kt b/src/main/kotlin/xyz/alexcrea/cuanvil/listener/AnvilResultListener.kt
index 22821589..7f9ef676 100644
--- a/src/main/kotlin/xyz/alexcrea/cuanvil/listener/AnvilResultListener.kt
+++ b/src/main/kotlin/xyz/alexcrea/cuanvil/listener/AnvilResultListener.kt
@@ -31,6 +31,7 @@ import xyz.alexcrea.cuanvil.listener.PrepareAnvilListener.Companion.ANVIL_INPUT_
 import xyz.alexcrea.cuanvil.listener.PrepareAnvilListener.Companion.ANVIL_INPUT_RIGHT
 import xyz.alexcrea.cuanvil.listener.PrepareAnvilListener.Companion.ANVIL_OUTPUT_SLOT
 import xyz.alexcrea.cuanvil.util.CustomRecipeUtil
+import xyz.alexcrea.cuanvil.util.MaterialUtil.isAir
 import xyz.alexcrea.cuanvil.util.MiniMessageUtil
 import xyz.alexcrea.cuanvil.util.anvil.AnvilLoreEditUtil
 import xyz.alexcrea.cuanvil.util.anvil.AnvilXpUtil
@@ -92,7 +93,7 @@ class AnvilResultListener : Listener {
         }
 
         // Rename
-        if (rightItem == null) {
+        if (rightItem.isAir) {
             val result = AnvilMergeLogic.doRenaming(view, player, leftItem)
             if (result.isEmpty()) return
 
@@ -106,7 +107,7 @@ class AnvilResultListener : Listener {
         }
 
         // Merge
-        val canMerge = leftItem.canMergeWith(rightItem)
+        val canMerge = leftItem.canMergeWith(rightItem!!)
         if (canMerge) {
             val result = AnvilMergeLogic.doMerge(view, player, leftItem, rightItem)