diff --git a/index.js b/index.js
index a4cfc21a8..7387ae290 100644
--- a/index.js
+++ b/index.js
@@ -9,7 +9,7 @@ var Invite = require( "./lib/invite.js" ).Invite;
 var PMChannel = require( "./lib/PMChannel.js" ).PMChannel;
 var WebSocket = require( 'ws' );
 
-exports.prototype.isUserID = function(id){
+exports.isUserID = function(id){
 	return ((id + "").length === 17 && !isNaN(id));
 }