diff --git a/src/de/steamwar/bungeecore/listeners/mods/Forge.java b/src/de/steamwar/bungeecore/listeners/mods/Forge.java
index 2a6a8ca..e94d21d 100644
--- a/src/de/steamwar/bungeecore/listeners/mods/Forge.java
+++ b/src/de/steamwar/bungeecore/listeners/mods/Forge.java
@@ -22,6 +22,7 @@ package de.steamwar.bungeecore.listeners.mods;
 import de.steamwar.bungeecore.BungeeCore;
 import de.steamwar.bungeecore.listeners.BasicListener;
 import de.steamwar.bungeecore.sql.Mod;
+import net.md_5.bungee.api.chat.TextComponent;
 import net.md_5.bungee.api.connection.PendingConnection;
 import net.md_5.bungee.api.event.LoginEvent;
 import net.md_5.bungee.api.event.ProxyPingEvent;
@@ -103,15 +104,24 @@ public class Forge extends BasicListener {
             //for more information see https://wiki.vg/Minecraft_Forge_Handshake#FML2_protocol_.281.13_-_Current.29
             Utils.VarInt channelLength = Utils.readVarInt(data, 0);
             int pos = channelLength.length;
-            assert new String(data, pos, channelLength.value).equals("fml:handshake");
+            if(!new String(data, pos, channelLength.value).equals("fml:handshake")) {
+                event.getConnection().disconnect(TextComponent.fromLegacyText("Invalid forge registry response (0x00)"));
+                return;
+            }
 
             Utils.VarInt length = Utils.readVarInt(data, pos);
             pos += length.length;
-            assert channelLength.length + channelLength.value + length.length + length.value == data.length;
+            if(channelLength.length + channelLength.value + length.length + length.value != data.length) {
+                event.getConnection().disconnect(TextComponent.fromLegacyText("Invalid forge registry response (0x01)"));
+                return;
+            }
 
             Utils.VarInt packetId = Utils.readVarInt(data, pos);
             pos += packetId.length;
-            assert packetId.value == 2;
+            if(packetId.value != 2) {
+                event.getConnection().disconnect(TextComponent.fromLegacyText("Invalid forge registry response (0x02)"));
+                return;
+            }
 
             Utils.VarInt modCount = Utils.readVarInt(data, pos);
             pos += modCount.length;