diff --git a/libraries/AP_HAL_Empty/UARTDriver.cpp b/libraries/AP_HAL_Empty/UARTDriver.cpp
index 6a3ac2f144..22effd0b1d 100644
--- a/libraries/AP_HAL_Empty/UARTDriver.cpp
+++ b/libraries/AP_HAL_Empty/UARTDriver.cpp
@@ -15,6 +15,7 @@ bool Empty::UARTDriver::tx_pending() { return false; }
 uint32_t Empty::UARTDriver::available() { return 0; }
 uint32_t Empty::UARTDriver::txspace() { return 1; }
 int16_t Empty::UARTDriver::read() { return -1; }
+bool Empty::UARTDriver::discard_input() { return false; }
 
 /* Empty implementations of Print virtual methods */
 size_t Empty::UARTDriver::write(uint8_t c) { return 0; }
diff --git a/libraries/AP_HAL_Empty/UARTDriver.h b/libraries/AP_HAL_Empty/UARTDriver.h
index d45f39d62d..e4ad9a4bd0 100644
--- a/libraries/AP_HAL_Empty/UARTDriver.h
+++ b/libraries/AP_HAL_Empty/UARTDriver.h
@@ -18,6 +18,7 @@ public:
     uint32_t available() override;
     uint32_t txspace() override;
     int16_t read() override;
+    bool discard_input() override;
 
     /* Empty implementations of Print virtual methods */
     size_t write(uint8_t c) override;