diff --git a/test.py b/test.py
index 6bf22b1..495610b 100644
--- a/test.py
+++ b/test.py
@@ -128,7 +128,7 @@ class ClearCacheInstatnceHandler(tornado.web.RequestHandler):
 class SaveInstanceHandler(tornado.web.RequestHandler):
     def get(self):
         instances = om.serialize_instance_config()
-        with open(os.path.join(root), instance_config_fp, "w") as f:
+        with open(os.path.join(root, instance_config_fp), "w") as f:
             f.write(json.dumps(instances))
         self.write("OK")