diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
index e6e4d5b6ab..0be1605d2f 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
@@ -6,6 +6,7 @@
 #include <AP_AHRS/AP_AHRS.h>
 #include <AP_Vehicle/AP_Vehicle.h>
 #include <GCS_MAVLink/GCS.h>
+#include <AP_RangeFinder/RangeFinder_Backend.h>
 
 extern const AP_HAL::HAL& hal;
 
@@ -35,13 +36,17 @@ void NavEKF3_core::readRangeFinder(void)
         // use data from two range finders if available
 
         for (uint8_t sensorIndex = 0; sensorIndex <= 1; sensorIndex++) {
-            if ((frontend->_rng.get_orientation(sensorIndex) == ROTATION_PITCH_270) && (frontend->_rng.status(sensorIndex) == RangeFinder::RangeFinder_Good)) {
+            AP_RangeFinder_Backend *sensor = frontend->_rng.get_backend(sensorIndex);
+            if (sensor == nullptr) {
+                continue;
+            }
+            if ((sensor->orientation() == ROTATION_PITCH_270) && (sensor->status() == RangeFinder::RangeFinder_Good)) {
                 rngMeasIndex[sensorIndex] ++;
                 if (rngMeasIndex[sensorIndex] > 2) {
                     rngMeasIndex[sensorIndex] = 0;
                 }
                 storedRngMeasTime_ms[sensorIndex][rngMeasIndex[sensorIndex]] = imuSampleTime_ms - 25;
-                storedRngMeas[sensorIndex][rngMeasIndex[sensorIndex]] = frontend->_rng.distance_cm(sensorIndex) * 0.01f;
+                storedRngMeas[sensorIndex][rngMeasIndex[sensorIndex]] = sensor->distance_cm() * 0.01f;
             }
 
             // check for three fresh samples
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp
index 15b7ec2c73..ff9cb7d5cf 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_PosVelFusion.cpp
@@ -7,6 +7,7 @@
 #include <AP_AHRS/AP_AHRS.h>
 #include <AP_Vehicle/AP_Vehicle.h>
 #include <GCS_MAVLink/GCS.h>
+#include <AP_RangeFinder/RangeFinder_Backend.h>
 
 extern const AP_HAL::HAL& hal;
 
@@ -753,10 +754,13 @@ void NavEKF3_core::selectHeightForFusion()
     // the corrected reading is the reading that would have been taken if the sensor was
     // co-located with the IMU
     if (rangeDataToFuse) {
-        Vector3f posOffsetBody = frontend->_rng.get_pos_offset(rangeDataDelayed.sensor_idx) - accelPosOffset;
-        if (!posOffsetBody.is_zero()) {
-            Vector3f posOffsetEarth = prevTnb.mul_transpose(posOffsetBody);
-            rangeDataDelayed.rng += posOffsetEarth.z / prevTnb.c.z;
+        AP_RangeFinder_Backend *sensor = frontend->_rng.get_backend(rangeDataDelayed.sensor_idx);
+        if (sensor != nullptr) {
+            Vector3f posOffsetBody = sensor->get_pos_offset() - accelPosOffset;
+            if (!posOffsetBody.is_zero()) {
+                Vector3f posOffsetEarth = prevTnb.mul_transpose(posOffsetBody);
+                rangeDataDelayed.rng += posOffsetEarth.z / prevTnb.c.z;
+            }
         }
     }