diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index 54c37e0e81..676ce1dd78 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -926,17 +926,13 @@ void AP_GPS::send_mavlink_gps2_raw(mavlink_channel_t chan)
         rtk_age_ms(1));
 }
 
-void AP_GPS::send_mavlink_gps_rtk(mavlink_channel_t chan)
+void AP_GPS::send_mavlink_gps_rtk(mavlink_channel_t chan, uint8_t inst)
 {
-    if (drivers[0] != nullptr && drivers[0]->highest_supported_status() > AP_GPS::GPS_OK_FIX_3D) {
-        drivers[0]->send_mavlink_gps_rtk(chan);
+    if (inst >= GPS_MAX_RECEIVERS) {
+        return;
     }
-}
-
-void AP_GPS::send_mavlink_gps2_rtk(mavlink_channel_t chan)
-{
-    if (drivers[1] != nullptr && drivers[1]->highest_supported_status() > AP_GPS::GPS_OK_FIX_3D) {
-        drivers[1]->send_mavlink_gps_rtk(chan);
+    if (drivers[inst] != nullptr && drivers[inst]->highest_supported_status() > AP_GPS::GPS_OK_FIX_3D) {
+        drivers[inst]->send_mavlink_gps_rtk(chan);
     }
 }
 
diff --git a/libraries/AP_GPS/AP_GPS.h b/libraries/AP_GPS/AP_GPS.h
index f19af60634..b021a6312c 100644
--- a/libraries/AP_GPS/AP_GPS.h
+++ b/libraries/AP_GPS/AP_GPS.h
@@ -363,8 +363,7 @@ public:
     void send_mavlink_gps_raw(mavlink_channel_t chan);
     void send_mavlink_gps2_raw(mavlink_channel_t chan);
 
-    void send_mavlink_gps_rtk(mavlink_channel_t chan);
-    void send_mavlink_gps2_rtk(mavlink_channel_t chan);
+    void send_mavlink_gps_rtk(mavlink_channel_t chan, uint8_t inst);
 
     // Returns the index of the first unconfigured GPS (returns GPS_ALL_CONFIGURED if all instances report as being configured)
     uint8_t first_unconfigured_gps(void) const;
diff --git a/libraries/AP_GPS/GPS_Backend.h b/libraries/AP_GPS/GPS_Backend.h
index 27e233d279..5b76a34166 100644
--- a/libraries/AP_GPS/GPS_Backend.h
+++ b/libraries/AP_GPS/GPS_Backend.h
@@ -44,9 +44,7 @@ public:
     virtual void inject_data(const uint8_t *data, uint16_t len);
 
     //MAVLink methods
-    virtual void send_mavlink_gps_rtk(mavlink_channel_t chan) { return ; }
-
-    virtual void send_mavlink_gps2_rtk(mavlink_channel_t chan) { return ; }
+    virtual void send_mavlink_gps_rtk(mavlink_channel_t chan);
 
     virtual void broadcast_configuration_failure_reason(void) const { return ; }