diff --git a/libraries/AP_Compass/AP_Compass_HMC5843.cpp b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
index a9c3d4b10c..6c8f917645 100644
--- a/libraries/AP_Compass/AP_Compass_HMC5843.cpp
+++ b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
@@ -126,6 +126,7 @@ AP_Compass_Backend *AP_Compass_HMC5843::probe(AP_HAL::OwnPtr<AP_HAL::Device> dev
     return sensor;
 }
 
+#if AP_INERTIALSENSOR_ENABLED
 AP_Compass_Backend *AP_Compass_HMC5843::probe_mpu6000(enum Rotation rotation)
 {
     AP_InertialSensor &ins = *AP_InertialSensor::get_singleton();
@@ -145,6 +146,7 @@ AP_Compass_Backend *AP_Compass_HMC5843::probe_mpu6000(enum Rotation rotation)
 
     return sensor;
 }
+#endif
 
 bool AP_Compass_HMC5843::init()
 {
@@ -488,6 +490,7 @@ AP_HAL::Device::PeriodicHandle AP_HMC5843_BusDriver_HALDevice::register_periodic
 }
 
 
+#if AP_INERTIALSENSOR_ENABLED
 /* HMC5843 on an auxiliary bus of IMU driver */
 AP_HMC5843_BusDriver_Auxiliary::AP_HMC5843_BusDriver_Auxiliary(AP_InertialSensor &ins, uint8_t backend_id,
                                                                uint8_t addr)
@@ -496,14 +499,12 @@ AP_HMC5843_BusDriver_Auxiliary::AP_HMC5843_BusDriver_Auxiliary(AP_InertialSensor
      * Only initialize members. Fails are handled by configure or while
      * getting the semaphore
      */
-#if AP_INERTIALSENSOR_ENABLED
     _bus = ins.get_auxiliary_bus(backend_id);
     if (!_bus) {
         return;
     }
 
     _slave = _bus->request_next_slave(addr);
-#endif
 }
 
 AP_HMC5843_BusDriver_Auxiliary::~AP_HMC5843_BusDriver_Auxiliary()
@@ -585,5 +586,6 @@ uint32_t AP_HMC5843_BusDriver_Auxiliary::get_bus_id(void) const
 {
     return _bus->get_bus_id();
 }
+#endif  // AP_INERTIALSENSOR_ENABLED
 
 #endif  // AP_COMPASS_HMC5843_ENABLED
diff --git a/libraries/AP_Compass/AP_Compass_HMC5843.h b/libraries/AP_Compass/AP_Compass_HMC5843.h
index e3427c2d3d..a2750c6cef 100644
--- a/libraries/AP_Compass/AP_Compass_HMC5843.h
+++ b/libraries/AP_Compass/AP_Compass_HMC5843.h
@@ -13,6 +13,7 @@
 #include <AP_HAL/Device.h>
 
 #include "AP_Compass_Backend.h"
+#include <AP_InertialSensor/AP_InertialSensor_config.h>
 
 class AuxiliaryBus;
 class AuxiliaryBusSlave;
@@ -26,7 +27,9 @@ public:
                                      bool force_external,
                                      enum Rotation rotation);
 
+#if AP_INERTIALSENSOR_ENABLED
     static AP_Compass_Backend *probe_mpu6000(enum Rotation rotation);
+#endif
 
     static constexpr const char *name = "HMC5843";
 
@@ -124,6 +127,7 @@ private:
     AP_HAL::OwnPtr<AP_HAL::Device> _dev;
 };
 
+#if AP_INERTIALSENSOR_ENABLED
 class AP_HMC5843_BusDriver_Auxiliary : public AP_HMC5843_BusDriver
 {
 public:
@@ -153,5 +157,6 @@ private:
     AuxiliaryBusSlave *_slave;
     bool _started;
 };
+#endif  // AP_INERTIALSENSOR_ENABLED
 
 #endif // AP_COMPASS_HMC5843_ENABLED