diff --git a/src/connection.ts b/src/connection.ts
index 85f919d40..05df1edda 100644
--- a/src/connection.ts
+++ b/src/connection.ts
@@ -11,7 +11,7 @@ const licenceKey = "";
 const SCHEMA = "ws://";
 
 type MsgboxCallback = (type: string, title: string, text: string) => void;
-type DrawCallback = (Uint8Array) => void;
+type DrawCallback = (data: Uint8Array) => void;
 
 export default class Connection {
   _msgs: any[];