diff --git a/a8/xobject.cc b/a8/xobject.cc
index 0af198d..4926092 100644
--- a/a8/xobject.cc
+++ b/a8/xobject.cc
@@ -424,7 +424,7 @@ namespace a8
     {
         if (type_ == a8::XOT_OBJECT) {
             for (auto& pair : *value_.object_value) {
-                kv_list[pair.first] = pair.second->AsXValue().GetString();
+                kv_list[pair.first + ""] = pair.second->AsXValue().GetString() + "";
             }
         }
     }