diff --git a/libraries/AP_Terrain/TerrainGCS.cpp b/libraries/AP_Terrain/TerrainGCS.cpp
index aca427cfec..e25a71fb41 100644
--- a/libraries/AP_Terrain/TerrainGCS.cpp
+++ b/libraries/AP_Terrain/TerrainGCS.cpp
@@ -16,12 +16,14 @@
   handle vehicle <-> GCS communications for terrain library
  */
 
+#include "AP_Terrain.h"
+
+#include <AP_AHRS/AP_AHRS.h>
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Common/AP_Common.h>
 #include <AP_Math/AP_Math.h>
 #include <GCS_MAVLink/GCS_MAVLink.h>
 #include <GCS_MAVLink/GCS.h>
-#include "AP_Terrain.h"
 
 #if AP_TERRAIN_AVAILABLE