diff --git a/libraries/AP_HAL_SITL/UARTDriver.cpp b/libraries/AP_HAL_SITL/UARTDriver.cpp
index 1a2c85aa0b..bbf15c3dea 100644
--- a/libraries/AP_HAL_SITL/UARTDriver.cpp
+++ b/libraries/AP_HAL_SITL/UARTDriver.cpp
@@ -176,7 +176,7 @@ int16_t UARTDriver::read(void)
 
 bool UARTDriver::discard_input(void)
 {
-    _readbuffer.empty();
+    _readbuffer.clear();
     return true;
 }