diff --git a/libraries/AP_AHRS/AP_AHRS.cpp b/libraries/AP_AHRS/AP_AHRS.cpp
index 1805993f0d..714ef56d53 100644
--- a/libraries/AP_AHRS/AP_AHRS.cpp
+++ b/libraries/AP_AHRS/AP_AHRS.cpp
@@ -38,9 +38,13 @@
 #define ATTITUDE_CHECK_THRESH_ROLL_PITCH_RAD radians(10)
 #define ATTITUDE_CHECK_THRESH_YAW_RAD radians(20)
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+#define HAL_AHRS_EKF_TYPE_DEFAULT 3
+#else
 #ifndef HAL_AHRS_EKF_TYPE_DEFAULT
 #define HAL_AHRS_EKF_TYPE_DEFAULT 2
 #endif
+#endif
 
 // table of user settable parameters
 const AP_Param::GroupInfo AP_AHRS::var_info[] = {
diff --git a/libraries/AP_AHRS/AP_AHRS.h b/libraries/AP_AHRS/AP_AHRS.h
index d41fbd4aaf..06d732d935 100644
--- a/libraries/AP_AHRS/AP_AHRS.h
+++ b/libraries/AP_AHRS/AP_AHRS.h
@@ -24,6 +24,11 @@
 #include <AP_HAL/AP_HAL_Boards.h>
 #include <AP_HAL/Semaphores.h>
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+#define HAL_NAVEKF2_AVAILABLE 1
+#define HAL_NAVEKF3_AVAILABLE 1
+#else
+
 #ifndef HAL_NAVEKF3_AVAILABLE
 // only default to EK2 enabled on boards with over 1M flash
 #define HAL_NAVEKF3_AVAILABLE (BOARD_FLASH_SIZE>1024)
@@ -32,6 +37,7 @@
 #ifndef HAL_NAVEKF2_AVAILABLE
 #define HAL_NAVEKF2_AVAILABLE 1
 #endif
+#endif
 
 #ifndef AP_AHRS_SIM_ENABLED
 #define AP_AHRS_SIM_ENABLED AP_SIM_ENABLED