diff --git a/src/core/Schemas.ts b/src/core/Schemas.ts
index 392ce7f99..8f202d9d0 100644
--- a/src/core/Schemas.ts
+++ b/src/core/Schemas.ts
@@ -371,42 +371,41 @@ export const ServerMessageSchema = z.union([
 
 // Client
 
-const ClientBaseMessageSchema = z.object({
-  type: z.enum(["winner", "join", "intent", "ping", "log", "hash"]),
-});
-
-export const ClientSendWinnerSchema = ClientBaseMessageSchema.extend({
+export const ClientSendWinnerSchema = z.object({
   type: z.literal("winner"),
   winner: z.union([ID, TeamSchema]).nullable(),
   allPlayersStats: AllPlayersStatsSchema,
   winnerType: z.enum(["player", "team"]),
 });
 
-export const ClientHashSchema = ClientBaseMessageSchema.extend({
+export const ClientHashSchema = z.object({
   type: z.literal("hash"),
   hash: z.number(),
   turnNumber: z.number(),
 });
 
-export const ClientLogMessageSchema = ClientBaseMessageSchema.extend({
+export const ClientLogMessageSchema = z.object({
   type: z.literal("log"),
   severity: z.nativeEnum(LogSeverity),
   log: ID,
   persistentID: SafeString,
 });
 
-export const ClientPingMessageSchema = ClientBaseMessageSchema.extend({
+export const ClientPingMessageSchema = z.object({
   type: z.literal("ping"),
 });
 
-export const ClientIntentMessageSchema = ClientBaseMessageSchema.extend({
+export const ClientIntentMessageSchema = z.object({
   type: z.literal("intent"),
   intent: IntentSchema,
 });
 
 // WARNING: never send this message to clients.
-export const ClientJoinMessageSchema = ClientBaseMessageSchema.extend({
+export const ClientJoinMessageSchema = z.object({
   type: z.literal("join"),
+  clientID: ID,
+  persistentID: SafeString, // WARNING: PII
+  gameID: ID,
   lastTurn: z.number(), // The last turn the client saw.
   username: SafeString,
   flag: SafeString.nullable().optional(),
diff --git a/src/server/Worker.ts b/src/server/Worker.ts
index 880dca263..0ce554f16 100644
--- a/src/server/Worker.ts
+++ b/src/server/Worker.ts
@@ -7,7 +7,7 @@ import { WebSocket, WebSocketServer } from "ws";
 import { GameEnv } from "../core/configuration/Config";
 import { getServerConfigFromServer } from "../core/configuration/ConfigLoader";
 import { GameType } from "../core/game/Game";
-import { GameConfig, GameRecord } from "../core/Schemas";
+import { ClientMessageSchema, GameConfig, GameRecord } from "../core/Schemas";
 import { archive, readGameRecord } from "./Archive";
 import { Client } from "./Client";
 import { GameManager } from "./GameManager";
@@ -263,7 +263,9 @@ export function startWorker() {
         try {
           // Process WebSocket messages as in your original code
           // Parse and handle client messages
-          const clientMsg = JSON.parse(message.toString());
+          const clientMsg = ClientMessageSchema.parse(
+            JSON.parse(message.toString()),
+          );
 
           if (clientMsg.type == "join") {
             // Verify this worker should handle this game