diff --git a/cloudron.js b/cloudron.js
index 514c090..12ea3e6 100644
--- a/cloudron.js
+++ b/cloudron.js
@@ -444,7 +444,7 @@ Cloudron.prototype.setAutoupdatePattern = function (pattern) {
 };
 
 Cloudron.prototype.checkA = function (callback) {
-    var expectedIp = this._isCustomDomain ? this._.staticIp : this._.ip;
+    var expectedIp = this._isCustomDomain ? this._box.staticIp : this._box.ip;
 
     dns.resolve4(this._box.domain, function (error, records) {
         if (error) return callback(error);