diff --git a/libraries/AP_HAL_Empty/I2CDriver.cpp b/libraries/AP_HAL_Empty/I2CDriver.cpp
index 215a64ad68..c8b7876756 100644
--- a/libraries/AP_HAL_Empty/I2CDriver.cpp
+++ b/libraries/AP_HAL_Empty/I2CDriver.cpp
@@ -1,4 +1,5 @@
 
+#include <AP_HAL.h>
 #include "I2CDriver.h"
 
 using namespace Empty;