diff --git a/src/core/game/Game.ts b/src/core/game/Game.ts
index eca72a9df..b3d546da0 100644
--- a/src/core/game/Game.ts
+++ b/src/core/game/Game.ts
@@ -549,7 +549,7 @@ export interface Game extends GameMap {
     unitID: number,
     message: string,
     type: MessageType,
-    playerID: PlayerID,
+    playerID: PlayerID | null,
   ): void;
 
   displayChat(