--- a/mailnews/test/fakeserver/smtpd.js
+++ b/mailnews/test/fakeserver/smtpd.js
@@ -71,17 +71,17 @@ SMTP_RFC2821_handler.prototype = {
     var scheme = args[0].toUpperCase();
     // |scheme| contained in |kAuthSchemes|?
     if (!this.kAuthSchemes.some(function (s) { return s == scheme; }))
       return "504 AUTH " + scheme + " not supported";
     var func = this._kAuthSchemeStartFunction[scheme];
     if (!func || typeof(func) != "function")
       return "504 I just pretended to implement AUTH " + scheme + ", but I don't";
     dump("Starting AUTH " + scheme + "\n");
-    return func.call(this, args[1]);
+    return func.call(this, ((args.length > 1) ? args[1] : undefined));
   },
   MAIL: function (args) {
     if (this._state == kStateAuthNeeded)
       return "530 5.7.0 Authentication required";
     return "250 ok";
   },
   RCPT: function(args) {
     if (this._state == kStateAuthNeeded)