diff --git a/EKF/ekf.h b/EKF/ekf.h
index e2bff69676..33b59263f1 100644
--- a/EKF/ekf.h
+++ b/EKF/ekf.h
@@ -256,7 +256,7 @@ public:
 	void get_ekf_soln_status(uint16_t *status);
 
 	// return the quaternion defining the rotation from the EKF to the External Vision reference frame
-	void get_ekf2ev_quaternion(float *quat);
+	void get_ev2ekf_quaternion(float *quat);
 
 	// use the latest IMU data at the current time horizon.
 	Quatf calculate_quaternion() const;
diff --git a/EKF/ekf_helper.cpp b/EKF/ekf_helper.cpp
index e4b0bc9b42..c1d0403e3d 100644
--- a/EKF/ekf_helper.cpp
+++ b/EKF/ekf_helper.cpp
@@ -1653,14 +1653,14 @@ void Ekf::resetExtVisRotMat()
 	_ev_rot_mat = Dcmf(q_error); // rotation from EV reference to EKF reference
 }
 
-// return the quaternions for the rotation from the EKF to the External Vision system frame of reference
-void Ekf::get_ekf2ev_quaternion(float *quat)
+// return the quaternions for the rotation from External Vision system reference frame to the EKF reference frame
+void Ekf::get_ev2ekf_quaternion(float *quat)
 {
-	Quatf quat_ekf2ev;
-	quat_ekf2ev.from_axis_angle(_ev_rot_vec_filt);
+	Quatf quat_ev2ekf;
+	quat_ev2ekf.from_axis_angle(_ev_rot_vec_filt);
 
 	for (unsigned i = 0; i < 4; i++) {
-		quat[i] = quat_ekf2ev(i);
+		quat[i] = quat_ev2ekf(i);
 	}
 }
 
diff --git a/EKF/estimator_interface.h b/EKF/estimator_interface.h
index 8ebb16c2f7..2ec93d8cc4 100644
--- a/EKF/estimator_interface.h
+++ b/EKF/estimator_interface.h
@@ -287,7 +287,7 @@ public:
 	const matrix::Quatf &get_quaternion() const { return _output_new.quat_nominal; }
 
 	// return the quaternion defining the rotation from the EKF to the External Vision reference frame
-	virtual void get_ekf2ev_quaternion(float *quat) = 0;
+	virtual void get_ev2ekf_quaternion(float *quat) = 0;
 
 	// get the velocity of the body frame origin in local NED earth frame
 	void get_velocity(float *vel)