diff --git a/libraries/AP_Compass/AP_Compass.cpp b/libraries/AP_Compass/AP_Compass.cpp
index dc7efcb57d0..a408da67648 100644
--- a/libraries/AP_Compass/AP_Compass.cpp
+++ b/libraries/AP_Compass/AP_Compass.cpp
@@ -1373,7 +1373,7 @@ void Compass::_detect_backends(void)
 #if AP_COMPASS_EXTERNALAHRS_ENABLED
     const int8_t serial_port = AP::externalAHRS().get_port(AP_ExternalAHRS::AvailableSensor::COMPASS);
     if (serial_port >= 0) {
-        ADD_BACKEND(DRIVER_EXTERNALAHRS, NEW_NOTHROW AP_Compass_ExternalAHRS(serial_port));
+        ADD_BACKEND(DRIVER_EXTERNALAHRS, AP_Compass_ExternalAHRS::probe(serial_port));
     }
 #endif
     
diff --git a/libraries/AP_Compass/AP_Compass_ExternalAHRS.cpp b/libraries/AP_Compass/AP_Compass_ExternalAHRS.cpp
index 87a57cd303d..af305afeb85 100644
--- a/libraries/AP_Compass/AP_Compass_ExternalAHRS.cpp
+++ b/libraries/AP_Compass/AP_Compass_ExternalAHRS.cpp
@@ -18,13 +18,20 @@
 
 #if AP_COMPASS_EXTERNALAHRS_ENABLED
 
-AP_Compass_ExternalAHRS::AP_Compass_ExternalAHRS(uint8_t port)
+AP_Compass_Backend *AP_Compass_ExternalAHRS::probe(uint8_t port)
 {
     auto devid = AP_HAL::Device::make_bus_id(AP_HAL::Device::BUS_TYPE_SERIAL,port,0,0);
-    register_compass(devid, instance);
-
-    set_dev_id(instance, devid);
-    set_external(instance, true);
+    auto *ret = NEW_NOTHROW AP_Compass_ExternalAHRS();
+    if (ret == nullptr) {
+        return nullptr;
+    }
+    if (!ret->register_compass(devid, ret->instance)) {
+        delete ret;
+        return nullptr;
+    }
+    ret->set_dev_id(ret->instance, devid);
+    ret->set_external(ret->instance, true);
+    return ret;
 }
 
 void AP_Compass_ExternalAHRS::handle_external(const AP_ExternalAHRS::mag_data_message_t &pkt)
diff --git a/libraries/AP_Compass/AP_Compass_ExternalAHRS.h b/libraries/AP_Compass/AP_Compass_ExternalAHRS.h
index 8162e7646ca..29e3367b366 100644
--- a/libraries/AP_Compass/AP_Compass_ExternalAHRS.h
+++ b/libraries/AP_Compass/AP_Compass_ExternalAHRS.h
@@ -11,7 +11,9 @@
 class AP_Compass_ExternalAHRS : public AP_Compass_Backend
 {
 public:
-    AP_Compass_ExternalAHRS(uint8_t instance);
+    using AP_Compass_Backend::AP_Compass_Backend;
+
+    static AP_Compass_Backend *probe(uint8_t port);
 
     void read(void) override;