diff --git a/hgdriver/hgdev/usb_manager.cpp b/hgdriver/hgdev/usb_manager.cpp
index 391779d..efb385f 100644
--- a/hgdriver/hgdev/usb_manager.cpp
+++ b/hgdriver/hgdev/usb_manager.cpp
@@ -633,7 +633,7 @@ bool usb_io::make_singleton(void)
 
     if (pos != std::string::npos)
         tips.replace(pos, 2, str);
-    str += std::move(tips);
+    str = std::move(tips);
     init_err_msg_ = str;
     VLOG_MINI_1(LOG_LEVEL_FATAL, "Open failed: %s\n", str.c_str());