diff --git a/src/dorkbox/network/serialization/ClassRegistration.kt b/src/dorkbox/network/serialization/ClassRegistration.kt
index 77d65dec..093c40a0 100644
--- a/src/dorkbox/network/serialization/ClassRegistration.kt
+++ b/src/dorkbox/network/serialization/ClassRegistration.kt
@@ -15,6 +15,7 @@
  */
 package dorkbox.network.serialization
 
+import com.esotericsoftware.kryo.Kryo
 import com.esotericsoftware.kryo.Serializer
 import dorkbox.network.rmi.messages.RmiServerSerializer
 
@@ -91,7 +92,7 @@ internal abstract class ClassRegistration(val clazz: Class<*>, val serializer: S
         rmi.implToId[clazz] = id
     }
 
-    open fun register(kryo: KryoExtra) {}
+    open fun register(kryo: Kryo) {}
 
     abstract fun getInfoArray(): Array<Any>
 }
diff --git a/src/dorkbox/network/serialization/ClassRegistration0.kt b/src/dorkbox/network/serialization/ClassRegistration0.kt
index 97bf78d4..a56f0686 100644
--- a/src/dorkbox/network/serialization/ClassRegistration0.kt
+++ b/src/dorkbox/network/serialization/ClassRegistration0.kt
@@ -15,10 +15,11 @@
  */
 package dorkbox.network.serialization
 
+import com.esotericsoftware.kryo.Kryo
 import com.esotericsoftware.kryo.Serializer
 
 internal class ClassRegistration0(clazz: Class<*>, serializer: Serializer<*>) : ClassRegistration(clazz, serializer) {
-    override fun register(kryo: KryoExtra) {
+    override fun register(kryo: Kryo) {
         id = kryo.register(clazz, serializer).id
         info = "Registered $id -> ${clazz.name} using ${serializer!!.javaClass.name}"
     }
diff --git a/src/dorkbox/network/serialization/ClassRegistration1.kt b/src/dorkbox/network/serialization/ClassRegistration1.kt
index b18b9d90..9b2a15e9 100644
--- a/src/dorkbox/network/serialization/ClassRegistration1.kt
+++ b/src/dorkbox/network/serialization/ClassRegistration1.kt
@@ -15,8 +15,10 @@
  */
 package dorkbox.network.serialization
 
+import com.esotericsoftware.kryo.Kryo
+
 internal class ClassRegistration1(clazz: Class<*>, id: Int) : ClassRegistration(clazz, null, id) {
-    override fun register(kryo: KryoExtra) {
+    override fun register(kryo: Kryo) {
         kryo.register(clazz, id)
         info = "Registered $id -> (specified) ${clazz.name}"
     }
diff --git a/src/dorkbox/network/serialization/ClassRegistration2.kt b/src/dorkbox/network/serialization/ClassRegistration2.kt
index dbb7481b..94e788f8 100644
--- a/src/dorkbox/network/serialization/ClassRegistration2.kt
+++ b/src/dorkbox/network/serialization/ClassRegistration2.kt
@@ -15,11 +15,12 @@
  */
 package dorkbox.network.serialization
 
+import com.esotericsoftware.kryo.Kryo
 import com.esotericsoftware.kryo.Serializer
 
 internal class ClassRegistration2(clazz: Class<*>, serializer: Serializer<*>, id: Int) : ClassRegistration(clazz, serializer, id) {
 
-    override fun register(kryo: KryoExtra) {
+    override fun register(kryo: Kryo) {
         kryo.register(clazz, serializer, id)
         info = "Registered $id -> (specified) ${clazz.name} using ${serializer!!.javaClass.name}"
     }
diff --git a/src/dorkbox/network/serialization/ClassRegistration3.kt b/src/dorkbox/network/serialization/ClassRegistration3.kt
index e10ec638..4248db64 100644
--- a/src/dorkbox/network/serialization/ClassRegistration3.kt
+++ b/src/dorkbox/network/serialization/ClassRegistration3.kt
@@ -15,9 +15,11 @@
  */
 package dorkbox.network.serialization
 
+import com.esotericsoftware.kryo.Kryo
+
 internal open class ClassRegistration3(clazz: Class<*>) : ClassRegistration(clazz) {
 
-    override fun register(kryo: KryoExtra) {
+    override fun register(kryo: Kryo) {
         id = kryo.register(clazz).id
         info = "Registered $id -> ${clazz.name}"
     }