diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index 96ac8a49bb..ed014d3303 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -1294,6 +1294,7 @@ void AP_GPS::update_primary(void)
 }
 #endif  // GPS_MAX_RECEIVERS > 1
 
+#if HAL_GCS_ENABLED
 void AP_GPS::handle_gps_inject(const mavlink_message_t &msg)
 {
     mavlink_gps_inject_data_t packet;
@@ -1331,6 +1332,7 @@ void AP_GPS::handle_msg(const mavlink_message_t &msg)
     }
     }
 }
+#endif
 
 #if HAL_MSP_GPS_ENABLED
 void AP_GPS::handle_msp(const MSP::msp_gps_data_message_t &pkt)
@@ -1496,6 +1498,7 @@ void AP_GPS::send_mavlink_gps2_raw(mavlink_channel_t chan)
 }
 #endif // GPS_MAX_RECEIVERS
 
+#if HAL_GCS_ENABLED
 void AP_GPS::send_mavlink_gps_rtk(mavlink_channel_t chan, uint8_t inst)
 {
     if (inst >= GPS_MAX_RECEIVERS) {
@@ -1505,6 +1508,7 @@ void AP_GPS::send_mavlink_gps_rtk(mavlink_channel_t chan, uint8_t inst)
         drivers[inst]->send_mavlink_gps_rtk(chan);
     }
 }
+#endif
 
 bool AP_GPS::first_unconfigured_gps(uint8_t &instance) const
 {
diff --git a/libraries/AP_GPS/AP_GPS_ERB.h b/libraries/AP_GPS/AP_GPS_ERB.h
index 8fb6f7ed0e..6e99fbe8e7 100644
--- a/libraries/AP_GPS/AP_GPS_ERB.h
+++ b/libraries/AP_GPS/AP_GPS_ERB.h
@@ -34,7 +34,9 @@ public:
 
     AP_GPS::GPS_Status highest_supported_status(void) override { return AP_GPS::GPS_OK_FIX_3D_RTK_FIXED; }
 
+#if HAL_GCS_ENABLED
     bool supports_mavlink_gps_rtk_message() const override { return true; }
+#endif
 
     static bool _detect(struct ERB_detect_state &state, uint8_t data);
 
diff --git a/libraries/AP_GPS/AP_GPS_SBF.h b/libraries/AP_GPS/AP_GPS_SBF.h
index ac4944a9cc..2d8d47baaf 100644
--- a/libraries/AP_GPS/AP_GPS_SBF.h
+++ b/libraries/AP_GPS/AP_GPS_SBF.h
@@ -45,7 +45,9 @@ public:
 
     void broadcast_configuration_failure_reason(void) const override;
 
+#if HAL_GCS_ENABLED
     bool supports_mavlink_gps_rtk_message(void) const override { return true; };
+#endif
 
     // get the velocity lag, returns true if the driver is confident in the returned value
     bool get_lag(float &lag_sec) const override { lag_sec = 0.08f; return true; } ;
diff --git a/libraries/AP_GPS/AP_GPS_SBP.h b/libraries/AP_GPS/AP_GPS_SBP.h
index 6ebeb1892d..a553588931 100644
--- a/libraries/AP_GPS/AP_GPS_SBP.h
+++ b/libraries/AP_GPS/AP_GPS_SBP.h
@@ -32,7 +32,9 @@ public:
 
     AP_GPS::GPS_Status highest_supported_status(void) override { return AP_GPS::GPS_OK_FIX_3D_RTK_FIXED; }
 
+#if HAL_GCS_ENABLED
     bool supports_mavlink_gps_rtk_message() const override { return true; }
+#endif
 
     // Methods
     bool read() override;
diff --git a/libraries/AP_GPS/GPS_Backend.cpp b/libraries/AP_GPS/GPS_Backend.cpp
index 3b442cffc8..249edacbc4 100644
--- a/libraries/AP_GPS/GPS_Backend.cpp
+++ b/libraries/AP_GPS/GPS_Backend.cpp
@@ -197,9 +197,9 @@ bool AP_GPS_Backend::should_log() const
 }
 
 
+#if HAL_GCS_ENABLED
 void AP_GPS_Backend::send_mavlink_gps_rtk(mavlink_channel_t chan)
 {
-#if HAL_GCS_ENABLED
     const uint8_t instance = state.instance;
     // send status
     switch (instance) {
@@ -236,8 +236,8 @@ void AP_GPS_Backend::send_mavlink_gps_rtk(mavlink_channel_t chan)
                                  state.rtk_iar_num_hypotheses);
             break;
     }
-#endif
 }
+#endif
 
 
 /*
diff --git a/libraries/AP_GPS/GPS_Backend.h b/libraries/AP_GPS/GPS_Backend.h
index ce1fac0d62..4f122b46ad 100644
--- a/libraries/AP_GPS/GPS_Backend.h
+++ b/libraries/AP_GPS/GPS_Backend.h
@@ -19,6 +19,7 @@
 #pragma once
 
 #include <GCS_MAVLink/GCS_MAVLink.h>
+#include <GCS_MAVLink/GCS_config.h>
 #include <AP_RTC/JitterCorrection.h>
 #include "AP_GPS.h"
 #include "AP_GPS_config.h"
@@ -55,13 +56,15 @@ public:
 
     virtual void inject_data(const uint8_t *data, uint16_t len);
 
+#if HAL_GCS_ENABLED
     //MAVLink methods
     virtual bool supports_mavlink_gps_rtk_message() const { return false; }
     virtual void send_mavlink_gps_rtk(mavlink_channel_t chan);
+    virtual void handle_msg(const mavlink_message_t &msg) { return ; }
+#endif
 
     virtual void broadcast_configuration_failure_reason(void) const { return ; }
 
-    virtual void handle_msg(const mavlink_message_t &msg) { return ; }
 #if HAL_MSP_GPS_ENABLED
     virtual void handle_msp(const MSP::msp_gps_data_message_t &pkt) { return; }
 #endif