diff --git a/libraries/AP_Mount/examples/trivial_AP_Mount/trivial_AP_Mount.pde b/libraries/AP_Mount/examples/trivial_AP_Mount/trivial_AP_Mount.pde
index 140f10f2f0..98ff40a514 100644
--- a/libraries/AP_Mount/examples/trivial_AP_Mount/trivial_AP_Mount.pde
+++ b/libraries/AP_Mount/examples/trivial_AP_Mount/trivial_AP_Mount.pde
@@ -18,6 +18,7 @@
 #include <Filter.h>
 #include <GCS_MAVLink.h>
 #include <AP_Mission.h>
+#include <AP_Terrain.h>
 #include <RC_Channel.h>
 #include <AP_Airspeed.h>
 #include <AP_Vehicle.h>