diff --git a/cloudron.js b/cloudron.js
index 4a09bee..b459af2 100644
--- a/cloudron.js
+++ b/cloudron.js
@@ -171,7 +171,7 @@ Cloudron.prototype.installApp = function (location, manifestOrAppstoreId, portBi
 
     var data = {
         manifest: typeof manifestOrAppstoreId === 'object' ? manifestOrAppstoreId : null,
-        appStoreId: typeof manifestOrAppstoreId === 'string' ? manifestOrAppstoreId : null,
+        appStoreId: typeof manifestOrAppstoreId === 'string' ? manifestOrAppstoreId : '',
         location: location,
         accessRestriction: null,
         oauthProxy: false,