diff --git a/src/serial_AT.cpp b/src/serial_AT.cpp
index 5eb8f12..ced5653 100644
--- a/src/serial_AT.cpp
+++ b/src/serial_AT.cpp
@@ -9,6 +9,7 @@
 
 #include "httplib.h"
 #include "logger.hpp"
+#include "nlohmann/json.hpp"
 #include "serial_port.h"
 
 // ================== 全局 IMEI ==================
@@ -67,18 +68,11 @@ void start_http_server(int port)
 
                           std::string imei = get_imei();
 
-                          std::ostringstream oss;
-                          oss << R"({
-                "ok": true,
-                "server": {
-                    "device_type": "tbox",
-                    "imei": ")"
-                              << imei << R"(",
-                    "fw": "b-v2.1.0"
-                }
-            })";
+                          nlohmann::json j;
+                          j["ok"] = true;
+                          j["server"] = {{"device_type", "tbox"}, {"imei", imei}, {"fw", "b-v2.1.0"}};
 
-                          res.set_content(oss.str(), "application/json");
+                          res.set_content(j.dump(2), "application/json");
                       });
 
     http_thread = std::thread(