diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
index 18f4158427..10e198a2d0 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_Measurements.cpp
@@ -145,6 +145,10 @@ void NavEKF2_core::writeOptFlowMeas(uint8_t &rawFlowQuality, Vector2f &rawFlowRa
 // check for new magnetometer data and update store measurements if available
 void NavEKF2_core::readMagData()
 {
+    if (!_ahrs->get_compass()) {
+        allMagSensorsFailed = true;
+        return;        
+    }
     // If we are a vehicle with a sideslip constraint to aid yaw estimation and we have timed out on our last avialable
     // magnetometer, then declare the magnetometers as failed for this flight
     uint8_t maxCount = _ahrs->get_compass()->get_count();
diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp
index 4369556ec7..e0977ebdbc 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_core.cpp
@@ -243,7 +243,9 @@ void NavEKF2_core::InitialiseVariables()
     posResetNE.zero();
     velResetNE.zero();
     hgtInnovFiltState = 0.0f;
-    magSelectIndex = _ahrs->get_compass()->get_primary();
+    if (_ahrs->get_compass()) {
+        magSelectIndex = _ahrs->get_compass()->get_primary();
+    }
     imuDataDownSampledNew.delAng.zero();
     imuDataDownSampledNew.delVel.zero();
     imuDataDownSampledNew.delAngDT = 0.0f;