diff --git a/cloudron.js b/cloudron.js
index 9b224a8..e68abe0 100644
--- a/cloudron.js
+++ b/cloudron.js
@@ -18,7 +18,8 @@ process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0';
 
 function Cloudron(box) {
     this._box = box;
-    this._origin = box.domain === process.env.CUSTOM_DOMAIN ? 'https://my.' + box.domain : 'https://my-' + box.domain;
+    this._isCustomDomain = box.domain === process.env.CUSTOM_DOMAIN;
+    this._origin = this._isCustomDomain ? 'https://my.' + box.domain : 'https://my-' + box.domain;
 
     this._credentials = {
         password: null,
@@ -26,6 +27,10 @@ function Cloudron(box) {
     };
 }
 
+Cloudron.prototype.appFqdn = function (location) {
+    return location + (this._isCustomDomain ? '.' : '-') + this._box.domain;
+};
+
 // get oauth token for logged in as certain user { username, password, email }
 Cloudron.prototype.getOauthToken = function (user) {
     var username = user.username;
@@ -313,7 +318,7 @@ Cloudron.prototype.checkAddons = function (location, owner) {
 
     // try many times because the scheduler takes sometime to run
     for (var i = 0; i < 100; i++) {
-        var res = request.post('https://' + location + '-' + this._box.domain + '/check_addons').query({ username: owner.username, password: owner.password }).end();
+        var res = request.post('https://' + this.appFqdn(location) + '/check_addons').query({ username: owner.username, password: owner.password }).end();
 
         try {
             assert.strictEqual(res.statusCode, 200);