diff --git a/modbus/modbus_block_host.cpp b/modbus/modbus_block_host.cpp
index 6c44133..8eb0aab 100644
--- a/modbus/modbus_block_host.cpp
+++ b/modbus/modbus_block_host.cpp
@@ -6,9 +6,6 @@ using namespace iflytop;
 ModbusBlockHost::ModbusBlockHost() {}
 ModbusBlockHost::~ModbusBlockHost() {}
 
-extern "C" {
-void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {}
-}
 
 void ModbusBlockHost::initialize(UART_HandleTypeDef *huart) {
   this->huart = huart;