--- a/app.go	Fri Apr 28 13:28:16 2017 +0200
+++ b/app.go	Fri Apr 28 15:43:11 2017 +0200
@@ -68,7 +68,7 @@
 	}
 
 	var app registerApp
-	if err := mc.apiCall("apps", rest.Post, params, &app); err != nil {
+	if err := mc.apiCall("apps", rest.Post, params, nil, &app); err != nil {
 		return nil, err
 	}