diff --git a/src/client/websocket/WebSocketShard.js b/src/client/websocket/WebSocketShard.js
index 763ba6b..c27f3bc 100644
--- a/src/client/websocket/WebSocketShard.js
+++ b/src/client/websocket/WebSocketShard.js
@@ -64,6 +64,7 @@ class WebSocketShard extends EventEmitter {
 
     /**
      * URL to use when resuming
+     * @type {?string}
      */
     this.resumeURL = null;