diff --git a/docs/en_us/0_Startup.md b/docs/en_us/0_Startup.md
index 50fd7c1..8fe83ec 100644
--- a/docs/en_us/0_Startup.md
+++ b/docs/en_us/0_Startup.md
@@ -24,7 +24,7 @@ Then add the include folder in the repository to your project's header search pa
 
 ```cpp
 // Import header file (default dependency on asio, macro need to be defined if use boost::asio)
-#define FV_USE_BOOST_ASIO
+//#define FV_USE_BOOST_ASIO
 #include <fv/fv.hpp>
 
 // Main function