diff --git a/pom.xml b/pom.xml
index eb51ed02..ad7d8918 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
 
     <groupId>com.github.steveice10</groupId>
     <artifactId>mcprotocollib</artifactId>
-    <version>1.16.3-1</version>
+    <version>1.16.4-pre1-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>MCProtocolLib</name>
diff --git a/src/main/java/com/github/steveice10/mc/protocol/MinecraftConstants.java b/src/main/java/com/github/steveice10/mc/protocol/MinecraftConstants.java
index baf37bc4..c3c93f6f 100644
--- a/src/main/java/com/github/steveice10/mc/protocol/MinecraftConstants.java
+++ b/src/main/java/com/github/steveice10/mc/protocol/MinecraftConstants.java
@@ -12,12 +12,13 @@ public final class MinecraftConstants {
     /**
      * Current supported game version.
      */
-    public static final String GAME_VERSION = "1.16.3";
+    public static final String GAME_VERSION = "1.16.4-pre1";
 
     /**
      * Current supported protocol version.
      */
-    public static final int PROTOCOL_VERSION = 753;
+    //public static final int PROTOCOL_VERSION = 754;
+    public static final int PROTOCOL_VERSION = (1 << 30) | 1;
 
     // General Key Constants
 
diff --git a/src/main/java/com/github/steveice10/mc/protocol/packet/ingame/client/window/ClientEditBookPacket.java b/src/main/java/com/github/steveice10/mc/protocol/packet/ingame/client/window/ClientEditBookPacket.java
index 199271c3..60f6e67a 100644
--- a/src/main/java/com/github/steveice10/mc/protocol/packet/ingame/client/window/ClientEditBookPacket.java
+++ b/src/main/java/com/github/steveice10/mc/protocol/packet/ingame/client/window/ClientEditBookPacket.java
@@ -1,8 +1,6 @@
 package com.github.steveice10.mc.protocol.packet.ingame.client.window;
 
-import com.github.steveice10.mc.protocol.data.MagicValues;
 import com.github.steveice10.mc.protocol.data.game.entity.metadata.ItemStack;
-import com.github.steveice10.mc.protocol.data.game.entity.player.Hand;
 import com.github.steveice10.packetlib.io.NetInput;
 import com.github.steveice10.packetlib.io.NetOutput;
 import com.github.steveice10.packetlib.packet.Packet;
@@ -22,20 +20,20 @@ import java.io.IOException;
 public class ClientEditBookPacket implements Packet {
     private @NonNull ItemStack book;
     private boolean signing;
-    private @NonNull Hand hand;
+    private int slot;
 
     @Override
     public void read(NetInput in) throws IOException {
         this.book = ItemStack.read(in);
         this.signing = in.readBoolean();
-        this.hand = MagicValues.key(Hand.class, in.readVarInt());
+        this.slot = in.readVarInt();
     }
 
     @Override
     public void write(NetOutput out) throws IOException {
         ItemStack.write(out, this.book);
         out.writeBoolean(this.signing);
-        out.writeVarInt(MagicValues.value(Integer.class, hand));
+        out.writeVarInt(slot);
     }
 
     @Override