diff --git a/libraries/AP_VisualOdom/AP_VisualOdom.cpp b/libraries/AP_VisualOdom/AP_VisualOdom.cpp
index 1aa8dfb7b5..485a367f2a 100644
--- a/libraries/AP_VisualOdom/AP_VisualOdom.cpp
+++ b/libraries/AP_VisualOdom/AP_VisualOdom.cpp
@@ -156,6 +156,7 @@ bool AP_VisualOdom::healthy() const
     return _driver->healthy();
 }
 
+#if HAL_GCS_ENABLED
 // consume vision_position_delta mavlink messages
 void AP_VisualOdom::handle_vision_position_delta_msg(const mavlink_message_t &msg)
 {
@@ -169,6 +170,7 @@ void AP_VisualOdom::handle_vision_position_delta_msg(const mavlink_message_t &ms
         _driver->handle_vision_position_delta_msg(msg);
     }
 }
+#endif
 
 // general purpose method to consume position estimate data and send to EKF
 // distances in meters, roll, pitch and yaw are in radians
diff --git a/libraries/AP_VisualOdom/AP_VisualOdom.h b/libraries/AP_VisualOdom/AP_VisualOdom.h
index 88bac3ac8c..20691d41c5 100644
--- a/libraries/AP_VisualOdom/AP_VisualOdom.h
+++ b/libraries/AP_VisualOdom/AP_VisualOdom.h
@@ -27,6 +27,7 @@
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Param/AP_Param.h>
 #include <GCS_MAVLink/GCS.h>
+#include <AP_Math/AP_Math.h>
 
 class AP_VisualOdom_Backend;
 
@@ -80,8 +81,10 @@ public:
     // return yaw measurement noise in rad
     float get_yaw_noise() const { return _yaw_noise; }
 
+#if HAL_GCS_ENABLED
     // consume vision_position_delta mavlink messages
     void handle_vision_position_delta_msg(const mavlink_message_t &msg);
+#endif
 
     // general purpose methods to consume position estimate data and send to EKF
     // distances in meters, roll, pitch and yaw are in radians