diff --git a/paper-api/src/main/java/org/bukkit/enchantments/EnchantmentOffer.java b/paper-api/src/main/java/org/bukkit/enchantments/EnchantmentOffer.java
index e99ed64451..da9fc59caa 100644
--- a/paper-api/src/main/java/org/bukkit/enchantments/EnchantmentOffer.java
+++ b/paper-api/src/main/java/org/bukkit/enchantments/EnchantmentOffer.java
@@ -60,8 +60,8 @@ public class EnchantmentOffer {
     }
 
     /**
-     * Gets the cost which is displayed as a number on the right hand side of
-     * the enchantment offer.
+     * Gets the cost (minimum level) which is displayed as a number on the right
+     * hand side of the enchantment offer.
      *
      * @return cost for this enchantment
      */
@@ -70,8 +70,8 @@ public class EnchantmentOffer {
     }
 
     /**
-     * Sets the the cost which is displayed as a number on the right hand side
-     * of the enchantment offer.
+     * Sets the the cost (minimum level) which is displayed as a number on the
+     * right hand side of the enchantment offer.
      *
      * @param cost cost for this enchantment
      */
diff --git a/paper-api/src/main/java/org/bukkit/event/enchantment/EnchantItemEvent.java b/paper-api/src/main/java/org/bukkit/event/enchantment/EnchantItemEvent.java
index 4ab67a55e4..f58e4599b7 100644
--- a/paper-api/src/main/java/org/bukkit/event/enchantment/EnchantItemEvent.java
+++ b/paper-api/src/main/java/org/bukkit/event/enchantment/EnchantItemEvent.java
@@ -2,6 +2,7 @@ package org.bukkit.event.enchantment;
 
 import java.util.HashMap;
 import java.util.Map;
+import org.apache.commons.lang.Validate;
 import org.bukkit.block.Block;
 import org.bukkit.enchantments.Enchantment;
 import org.bukkit.entity.Player;
@@ -24,7 +25,7 @@ public class EnchantItemEvent extends InventoryEvent implements Cancellable {
     private boolean cancelled;
     private final Map<Enchantment,Integer> enchants;
     private final Player enchanter;
-    private int button;
+    private final int button;
 
     public EnchantItemEvent(@NotNull final Player enchanter, @NotNull final InventoryView view, @NotNull final Block table, @NotNull final ItemStack item, final int level, @NotNull final Map<Enchantment, Integer> enchants, final int i) {
         super(view);
@@ -68,7 +69,8 @@ public class EnchantItemEvent extends InventoryEvent implements Cancellable {
     }
 
     /**
-     * Get cost in exp levels of the enchantment
+     * Gets the cost (minimum level) which is displayed as a number on the right
+     * hand side of the enchantment offer.
      *
      * @return experience level cost
      */
@@ -77,11 +79,14 @@ public class EnchantItemEvent extends InventoryEvent implements Cancellable {
     }
 
     /**
-     * Set cost in exp levels of the enchantment
+     * Sets the the cost (minimum level) which is displayed as a number on the
+     * right hand side of the enchantment offer.
      *
      * @param level - cost in levels
      */
     public void setExpLevelCost(int level) {
+        Validate.isTrue(level > 0, "The cost must be greater than 0!");
+
         this.level = level;
     }