diff --git a/cloudron.js b/cloudron.js
index b459af2..f3f0b0e 100644
--- a/cloudron.js
+++ b/cloudron.js
@@ -241,7 +241,7 @@ Cloudron.prototype.updateApp = function (appId, manifestOrAppstoreId) {
     var data = {
         password: this._credentials.password,
         manifest: typeof manifestOrAppstoreId === 'object' ? manifestOrAppstoreId : null,
-        appStoreId: typeof manifestOrAppstoreId === 'string' ? manifestOrAppstoreId : null
+        appStoreId: typeof manifestOrAppstoreId === 'string' ? manifestOrAppstoreId : ''
     };
 
     var res = request.post(this._origin + '/api/v1/apps/' + appId + '/update')