diff --git a/src/main/scala/li/cil/oc/server/component/UpgradeExperience.scala b/src/main/scala/li/cil/oc/server/component/UpgradeExperience.scala
index ebaf9b735..7f924a3a8 100644
--- a/src/main/scala/li/cil/oc/server/component/UpgradeExperience.scala
+++ b/src/main/scala/li/cil/oc/server/component/UpgradeExperience.scala
@@ -24,6 +24,8 @@ import scala.collection.convert.WrapAsJava._
 import scala.collection.convert.WrapAsScala._
 
 class UpgradeExperience(val host: EnvironmentHost with internal.Agent) extends prefab.ManagedEnvironment with DeviceInfo {
+  final val MaxLevel = 30
+
   override val node = api.Network.newNode(this, Visibility.Network).
     withComponent("experience").
     withConnector(30 * Settings.get.bufferPerLevel).
@@ -50,7 +52,7 @@ class UpgradeExperience(val host: EnvironmentHost with internal.Agent) extends p
   def xpForNextLevel = xpForLevel(level + 1)
 
   def addExperience(value: Double) {
-    if (level < 30) {
+    if (level < MaxLevel) {
       experience = experience + value
       if (experience >= xpForNextLevel) {
         updateXpInfo()
@@ -76,6 +78,9 @@ class UpgradeExperience(val host: EnvironmentHost with internal.Agent) extends p
 
   @Callback(doc = """function():boolean -- Tries to consume an enchanted item to add experience to the upgrade.""")
   def consume(context: Context, args: Arguments): Array[AnyRef] = {
+    if (level >= MaxLevel) {
+      return result(Unit, "max level")
+    }
     val stack = host.mainInventory.getStackInSlot(host.selectedSlot)
     if (stack == null || stack.stackSize < 1) {
       return result(Unit, "no item")