diff --git a/sw/airborne/subsystems/ahrs/ahrs_sim.c b/sw/airborne/subsystems/ahrs/ahrs_sim.c
index ea399730a0..f92cb3bbbc 100644
--- a/sw/airborne/subsystems/ahrs/ahrs_sim.c
+++ b/sw/airborne/subsystems/ahrs/ahrs_sim.c
@@ -47,7 +47,9 @@ void compute_body_orientation_and_rates(void);
 void update_attitude_from_sim(void) {
   ahrs_float.ltp_to_imu_euler.phi = sim_phi;
   ahrs_float.ltp_to_imu_euler.theta = sim_theta;
-  ahrs_float.ltp_to_imu_euler.psi = sim_psi;
+  ahrs_float.ltp_to_imu_euler.psi = -sim_psi;
+  FLOAT_ANGLE_NORMALIZE(ahrs_float.ltp_to_imu_euler.psi);
+  ahrs_float.ltp_to_imu_euler.psi += M_PI/2.;
 
   /* set quaternion and rotation matrix representations as well */
   FLOAT_QUAT_OF_EULERS(ahrs_float.ltp_to_imu_quat, ahrs_float.ltp_to_imu_euler);