diff --git a/libraries/AP_HAL_Empty/HAL_Empty_Class.cpp b/libraries/AP_HAL_Empty/HAL_Empty_Class.cpp
index d234016f5f..0594b515b3 100644
--- a/libraries/AP_HAL_Empty/HAL_Empty_Class.cpp
+++ b/libraries/AP_HAL_Empty/HAL_Empty_Class.cpp
@@ -26,6 +26,7 @@ HAL_Empty::HAL_Empty() :
         &uartADriver,
         &uartBDriver,
         &uartCDriver,
+        NULL,            /* no uartD */
         &i2cDriver,
         &spiDeviceManager,
         &analogIn,