diff --git a/cloudron.js b/cloudron.js
index 934a5a9..1c56f7b 100644
--- a/cloudron.js
+++ b/cloudron.js
@@ -401,7 +401,7 @@ Cloudron.prototype.checkMX = function (callback) {
         if (error) return callback(error);
         if (records.length !== 1) return callback(new Error('Got ' + JSON.stringify(records) + ' MX records. Expecting 1 length array'));
 
-        if (records[0].exchange !== this._adminFqdn) return callback(new Error('Bad MX record. ' + records[0]));
+        if (records[0].exchange !== that._adminFqdn) return callback(new Error('Bad MX record. ' + JSON.stringify(records[0])));
 
         callback(null, records);
     });