diff --git a/APMrover2/GCS_Mavlink.cpp b/APMrover2/GCS_Mavlink.cpp
index b157e332f4..2e66290c0c 100644
--- a/APMrover2/GCS_Mavlink.cpp
+++ b/APMrover2/GCS_Mavlink.cpp
@@ -620,13 +620,13 @@ MAV_RESULT GCS_MAVLINK_Rover::handle_command_long_packet(const mavlink_command_l
     switch (packet.command) {
 
     case MAV_CMD_NAV_RETURN_TO_LAUNCH:
-        if (rover.set_mode(rover.mode_rtl, MODE_REASON_GCS_COMMAND)) {
+        if (rover.set_mode(rover.mode_rtl, ModeReason::GCS_COMMAND)) {
             return MAV_RESULT_ACCEPTED;
         }
         return MAV_RESULT_FAILED;
 
     case MAV_CMD_MISSION_START:
-        if (rover.set_mode(rover.mode_auto, MODE_REASON_GCS_COMMAND)) {
+        if (rover.set_mode(rover.mode_auto, ModeReason::GCS_COMMAND)) {
             return MAV_RESULT_ACCEPTED;
         }
         return MAV_RESULT_FAILED;
@@ -1092,12 +1092,3 @@ void Rover::mavlink_delay_cb()
 
     logger.EnableWrites(true);
 }
-
-bool GCS_MAVLINK_Rover::set_mode(const uint8_t mode)
-{
-    Mode *new_mode = rover.mode_from_mode_num((enum Mode::Number)mode);
-    if (new_mode == nullptr) {
-        return false;
-    }
-    return rover.set_mode(*new_mode, MODE_REASON_GCS_COMMAND);
-}
diff --git a/APMrover2/GCS_Mavlink.h b/APMrover2/GCS_Mavlink.h
index b5131e8a65..bfe4f16445 100644
--- a/APMrover2/GCS_Mavlink.h
+++ b/APMrover2/GCS_Mavlink.h
@@ -15,8 +15,6 @@ protected:
     uint8_t sysid_my_gcs() const override;
     bool sysid_enforce() const override;
 
-    bool set_mode(uint8_t mode) override;
-
     MAV_RESULT _handle_command_preflight_calibration(const mavlink_command_long_t &packet) override;
     MAV_RESULT handle_command_int_packet(const mavlink_command_int_t &packet) override;
     MAV_RESULT handle_command_long_packet(const mavlink_command_long_t &packet) override;
diff --git a/APMrover2/RC_Channel.cpp b/APMrover2/RC_Channel.cpp
index 49e669abe0..12d59b087e 100644
--- a/APMrover2/RC_Channel.cpp
+++ b/APMrover2/RC_Channel.cpp
@@ -23,7 +23,7 @@ void RC_Channel_Rover::mode_switch_changed(modeswitch_pos_t new_pos)
     }
     Mode *new_mode = rover.mode_from_mode_num((Mode::Number)rover.modes[new_pos].get());
     if (new_mode != nullptr) {
-        rover.set_mode(*new_mode, MODE_REASON_TX_COMMAND);
+        rover.set_mode(*new_mode, ModeReason::RC_COMMAND);
     }
 }
 
@@ -71,7 +71,7 @@ void RC_Channel_Rover::do_aux_function_change_mode(Mode &mode,
 {
     switch (ch_flag) {
     case HIGH:
-        rover.set_mode(mode, MODE_REASON_TX_COMMAND);
+        rover.set_mode(mode, ModeReason::RC_COMMAND);
         break;
     case MIDDLE:
         // do nothing
diff --git a/APMrover2/Rover.h b/APMrover2/Rover.h
index 4dda42d697..789572bb6a 100644
--- a/APMrover2/Rover.h
+++ b/APMrover2/Rover.h
@@ -214,7 +214,7 @@ private:
     // This is the state of the flight control system
     // There are multiple states defined such as MANUAL, AUTO, ...
     Mode *control_mode;
-    mode_reason_t control_mode_reason = MODE_REASON_INITIALISED;
+    ModeReason control_mode_reason = ModeReason::UNKNOWN;
 
     // Used to maintain the state of the previous control switch position
     // This is set to -1 when we need to re-read the switch
@@ -401,7 +401,8 @@ private:
     void init_ardupilot();
     void startup_ground(void);
     void update_ahrs_flyforward();
-    bool set_mode(Mode &new_mode, mode_reason_t reason);
+    bool set_mode(Mode &new_mode, ModeReason reason);
+    bool set_mode(const uint8_t new_mode, ModeReason reason) override;
     bool mavlink_set_mode(uint8_t mode);
     void startup_INS_ground(void);
     void notify_mode(const Mode *new_mode);
diff --git a/APMrover2/crash_check.cpp b/APMrover2/crash_check.cpp
index 37d4e10c2a..9752668c7c 100644
--- a/APMrover2/crash_check.cpp
+++ b/APMrover2/crash_check.cpp
@@ -56,7 +56,7 @@ void Rover::crash_check()
             // send message to gcs
             gcs().send_text(MAV_SEVERITY_EMERGENCY, "Crash: Going to HOLD");
             // change mode to hold and disarm
-            set_mode(mode_hold, MODE_REASON_CRASH_FAILSAFE);
+            set_mode(mode_hold, ModeReason::CRASH_FAILSAFE);
             if (g.fs_crash_check == FS_CRASH_HOLD_AND_DISARM) {
                 arming.disarm();
             }
diff --git a/APMrover2/defines.h b/APMrover2/defines.h
index 2b9c907813..90dda0c1d2 100644
--- a/APMrover2/defines.h
+++ b/APMrover2/defines.h
@@ -90,18 +90,6 @@ enum fs_ekf_action {
 
 #define DISTANCE_HOME_MINCHANGE 0.5f  // minimum distance to adjust home location
 
-enum mode_reason_t {
-    MODE_REASON_INITIALISED = 0,
-    MODE_REASON_TX_COMMAND,
-    MODE_REASON_GCS_COMMAND,
-    MODE_REASON_FAILSAFE,
-    MODE_REASON_MISSION_END,
-    MODE_REASON_CRASH_FAILSAFE,
-    MODE_REASON_MISSION_COMMAND,
-    MODE_REASON_FENCE_BREACH,
-    MODE_REASON_EKF_FAILSAFE,
-};
-
 enum pilot_steer_type_t {
     PILOT_STEER_TYPE_DEFAULT = 0,
     PILOT_STEER_TYPE_TWO_PADDLES = 1,
diff --git a/APMrover2/ekf_check.cpp b/APMrover2/ekf_check.cpp
index e43c4f2ad2..ebb46f800d 100644
--- a/APMrover2/ekf_check.cpp
+++ b/APMrover2/ekf_check.cpp
@@ -167,7 +167,7 @@ void Rover::failsafe_ekf_event()
             break;
         case FS_EFK_HOLD:
         default:
-            set_mode(mode_hold, MODE_REASON_EKF_FAILSAFE);
+            set_mode(mode_hold, ModeReason::EKF_FAILSAFE);
             break;
     }
 }
diff --git a/APMrover2/failsafe.cpp b/APMrover2/failsafe.cpp
index fdf557a111..574e282653 100644
--- a/APMrover2/failsafe.cpp
+++ b/APMrover2/failsafe.cpp
@@ -84,23 +84,23 @@ void Rover::failsafe_trigger(uint8_t failsafe_type, bool on)
             case Failsafe_Action_None:
                 break;
             case Failsafe_Action_RTL:
-                if (!set_mode(mode_rtl, MODE_REASON_FAILSAFE)) {
-                    set_mode(mode_hold, MODE_REASON_FAILSAFE);
+                if (!set_mode(mode_rtl, ModeReason::FAILSAFE)) {
+                    set_mode(mode_hold, ModeReason::FAILSAFE);
                 }
                 break;
             case Failsafe_Action_Hold:
-                set_mode(mode_hold, MODE_REASON_FAILSAFE);
+                set_mode(mode_hold, ModeReason::FAILSAFE);
                 break;
             case Failsafe_Action_SmartRTL:
-                if (!set_mode(mode_smartrtl, MODE_REASON_FAILSAFE)) {
-                    if (!set_mode(mode_rtl, MODE_REASON_FAILSAFE)) {
-                        set_mode(mode_hold, MODE_REASON_FAILSAFE);
+                if (!set_mode(mode_smartrtl, ModeReason::FAILSAFE)) {
+                    if (!set_mode(mode_rtl, ModeReason::FAILSAFE)) {
+                        set_mode(mode_hold, ModeReason::FAILSAFE);
                     }
                 }
                 break;
             case Failsafe_Action_SmartRTL_Hold:
-                if (!set_mode(mode_smartrtl, MODE_REASON_FAILSAFE)) {
-                    set_mode(mode_hold, MODE_REASON_FAILSAFE);
+                if (!set_mode(mode_smartrtl, ModeReason::FAILSAFE)) {
+                    set_mode(mode_hold, ModeReason::FAILSAFE);
                 }
                 break;
             }
@@ -114,21 +114,21 @@ void Rover::handle_battery_failsafe(const char* type_str, const int8_t action)
             case Failsafe_Action_None:
                 break;
             case Failsafe_Action_SmartRTL:
-                if (set_mode(mode_smartrtl, MODE_REASON_FAILSAFE)) {
+                if (set_mode(mode_smartrtl, ModeReason::BATTERY_FAILSAFE)) {
                     break;
                 }
                 FALLTHROUGH;
             case Failsafe_Action_RTL:
-                if (set_mode(mode_rtl, MODE_REASON_FAILSAFE)) {
+                if (set_mode(mode_rtl, ModeReason::BATTERY_FAILSAFE)) {
                     break;
                 }
                 FALLTHROUGH;
             case Failsafe_Action_Hold:
-                set_mode(mode_hold, MODE_REASON_FAILSAFE);
+                set_mode(mode_hold, ModeReason::BATTERY_FAILSAFE);
                 break;
             case Failsafe_Action_SmartRTL_Hold:
-                if (!set_mode(mode_smartrtl, MODE_REASON_FAILSAFE)) {
-                    set_mode(mode_hold, MODE_REASON_FAILSAFE);
+                if (!set_mode(mode_smartrtl, ModeReason::BATTERY_FAILSAFE)) {
+                    set_mode(mode_hold, ModeReason::BATTERY_FAILSAFE);
                 }
                 break;
             case Failsafe_Action_Terminate:
diff --git a/APMrover2/fence.cpp b/APMrover2/fence.cpp
index 792ed75f16..b146ea967e 100644
--- a/APMrover2/fence.cpp
+++ b/APMrover2/fence.cpp
@@ -20,12 +20,12 @@ void Rover::fence_check()
         if (g2.fence.get_action() != AC_FENCE_ACTION_REPORT_ONLY) {
             // if we are within 100m of the fence, RTL
             if (g2.fence.get_breach_distance(new_breaches) <= AC_FENCE_GIVE_UP_DISTANCE) {
-                if (!set_mode(mode_rtl, MODE_REASON_FENCE_BREACH)) {
-                    set_mode(mode_hold, MODE_REASON_FENCE_BREACH);
+                if (!set_mode(mode_rtl, ModeReason::FENCE_BREACHED)) {
+                    set_mode(mode_hold, ModeReason::FENCE_BREACHED);
                 }
             } else {
                 // if more than 100m outside the fence just force to HOLD
-                set_mode(mode_hold, MODE_REASON_FENCE_BREACH);
+                set_mode(mode_hold, ModeReason::FENCE_BREACHED);
             }
         }
         AP::logger().Write_Error(LogErrorSubsystem::FAILSAFE_FENCE, LogErrorCode(new_breaches));
diff --git a/APMrover2/mode.h b/APMrover2/mode.h
index e9ded46aea..b83cb908e6 100644
--- a/APMrover2/mode.h
+++ b/APMrover2/mode.h
@@ -18,7 +18,7 @@ public:
 
     // Auto Pilot modes
     // ----------------
-    enum Number {
+    enum Number : uint8_t {
         MANUAL       = 0,
         ACRO         = 1,
         STEERING     = 3,
diff --git a/APMrover2/mode_auto.cpp b/APMrover2/mode_auto.cpp
index 75ff6e41c5..eee6c7dc67 100644
--- a/APMrover2/mode_auto.cpp
+++ b/APMrover2/mode_auto.cpp
@@ -441,7 +441,7 @@ void ModeAuto::exit_mission()
         return;
     }
 
-    if (g2.mis_done_behave == MIS_DONE_BEHAVE_ACRO && rover.set_mode(rover.mode_acro, MODE_REASON_MISSION_END)) {
+    if (g2.mis_done_behave == MIS_DONE_BEHAVE_ACRO && rover.set_mode(rover.mode_acro, ModeReason::MISSION_END)) {
         return;
     }
 
diff --git a/APMrover2/system.cpp b/APMrover2/system.cpp
index f38e946cbe..7368984d9d 100644
--- a/APMrover2/system.cpp
+++ b/APMrover2/system.cpp
@@ -150,7 +150,7 @@ void Rover::init_ardupilot()
     if (initial_mode == nullptr) {
         initial_mode = &mode_initializing;
     }
-    set_mode(*initial_mode, MODE_REASON_INITIALISED);
+    set_mode(*initial_mode, ModeReason::INITIALISED);
 
     // initialise rc channels
     rc().init();
@@ -173,7 +173,7 @@ void Rover::init_ardupilot()
 //*********************************************************************************
 void Rover::startup_ground(void)
 {
-    set_mode(mode_initializing, MODE_REASON_INITIALISED);
+    set_mode(mode_initializing, ModeReason::INITIALISED);
 
     gcs().send_text(MAV_SEVERITY_INFO, "<startup_ground> Ground start");
 
@@ -240,7 +240,7 @@ void Rover::update_ahrs_flyforward()
     ahrs.set_fly_forward(flyforward);
 }
 
-bool Rover::set_mode(Mode &new_mode, mode_reason_t reason)
+bool Rover::set_mode(Mode &new_mode, ModeReason reason)
 {
     if (control_mode == &new_mode) {
         // don't switch modes if we are already in the correct mode.
@@ -277,6 +277,16 @@ bool Rover::set_mode(Mode &new_mode, mode_reason_t reason)
     return true;
 }
 
+bool Rover::set_mode(const uint8_t new_mode, ModeReason reason)
+{
+    static_assert(sizeof(Mode::Number) == sizeof(new_mode), "The new mode can't be mapped to the vehicles mode number");
+    Mode *mode = rover.mode_from_mode_num((enum Mode::Number)new_mode);
+    if (mode == nullptr) {
+        return false;
+    }
+    return rover.set_mode(*mode, reason);
+}
+
 void Rover::startup_INS_ground(void)
 {
     gcs().send_text(MAV_SEVERITY_INFO, "Beginning INS calibration. Do not move vehicle");