diff --git a/libraries/AP_NavEKF2/AP_NavEKF2.cpp b/libraries/AP_NavEKF2/AP_NavEKF2.cpp
index 5e95046599..17d2dc3485 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2.cpp
@@ -819,20 +819,20 @@ uint32_t NavEKF2::getLastYawResetAngle(float &yawAng) const
 
 // return the amount of NE position change due to the last position reset in metres
 // returns the time of the last reset or 0 if no reset has ever occurred
-uint32_t NavEKF2::getLastPosNorthEastReset(Vector2f &pos)
+uint32_t NavEKF2::getLastPosNorthEastReset(Vector2f &pos) const
 {
     if (!core) {
-        return false;
+        return 0;
     }
     return core->getLastPosNorthEastReset(pos);
 }
 
 // return the amount of NE velocity change due to the last velocity reset in metres/sec
 // returns the time of the last reset or 0 if no reset has ever occurred
-uint32_t NavEKF2::getLastVelNorthEastReset(Vector2f &vel)
+uint32_t NavEKF2::getLastVelNorthEastReset(Vector2f &vel) const
 {
     if (!core) {
-        return false;
+        return 0;
     }
     return core->getLastVelNorthEastReset(vel);
 }
diff --git a/libraries/AP_NavEKF2/AP_NavEKF2.h b/libraries/AP_NavEKF2/AP_NavEKF2.h
index 5ce742f33c..8cd0ac9f71 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2.h
+++ b/libraries/AP_NavEKF2/AP_NavEKF2.h
@@ -229,11 +229,11 @@ public:
 
     // return the amount of NE position change due to the last position reset in metres
     // returns the time of the last reset or 0 if no reset has ever occurred
-    uint32_t getLastPosNorthEastReset(Vector2f &pos);
+    uint32_t getLastPosNorthEastReset(Vector2f &pos) const;
 
     // return the amount of NE velocity change due to the last velocity reset in metres/sec
     // returns the time of the last reset or 0 if no reset has ever occurred
-    uint32_t getLastVelNorthEastReset(Vector2f &vel);
+    uint32_t getLastVelNorthEastReset(Vector2f &vel) const;
 
     // allow the enable flag to be set by Replay
     void set_enable(bool enable) { _enable.set(enable); }
diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp
index 10f61d1717..bc6e2a5380 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_Outputs.cpp
@@ -130,7 +130,7 @@ uint32_t NavEKF2_core::getLastYawResetAngle(float &yawAng) const
 
 // return the amount of NE position change due to the last position reset in metres
 // returns the time of the last reset or 0 if no reset has ever occurred
-uint32_t NavEKF2_core::getLastPosNorthEastReset(Vector2f &pos)
+uint32_t NavEKF2_core::getLastPosNorthEastReset(Vector2f &pos) const
 {
     pos = posResetNE;
     return lastPosReset_ms;
@@ -138,7 +138,7 @@ uint32_t NavEKF2_core::getLastPosNorthEastReset(Vector2f &pos)
 
 // return the amount of NE velocity change due to the last velocity reset in metres/sec
 // returns the time of the last reset or 0 if no reset has ever occurred
-uint32_t NavEKF2_core::getLastVelNorthEastReset(Vector2f &vel)
+uint32_t NavEKF2_core::getLastVelNorthEastReset(Vector2f &vel) const
 {
     vel = velResetNE;
     return lastVelReset_ms;
diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_core.h b/libraries/AP_NavEKF2/AP_NavEKF2_core.h
index 52a8a2c28e..1ba4aafa94 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_core.h
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_core.h
@@ -250,11 +250,11 @@ public:
 
     // return the amount of NE position change due to the last position reset in metres
     // returns the time of the last reset or 0 if no reset has ever occurred
-    uint32_t getLastPosNorthEastReset(Vector2f &pos);
+    uint32_t getLastPosNorthEastReset(Vector2f &pos) const;
 
     // return the amount of NE velocity change due to the last velocity reset in metres/sec
     // returns the time of the last reset or 0 if no reset has ever occurred
-    uint32_t getLastVelNorthEastReset(Vector2f &vel);
+    uint32_t getLastVelNorthEastReset(Vector2f &vel) const;
 
 private:
     // Reference to the global EKF frontend for parameters