diff --git a/src/pyFAI/units.py b/src/pyFAI/units.py
index 0ffd1f670..f0190adaa 100644
--- a/src/pyFAI/units.py
+++ b/src/pyFAI/units.py
@@ -778,7 +778,6 @@ def eq_chi_gi(x, y, z, wavelength, incident_angle=0.0, tilt_angle=0.0, sample_or
 formula_exit_angle_vert = f"arctan2({formula_y_rot_tangle}, sqrt({formula_z_rot_tangle} * {formula_z_rot_tangle} + {formula_x_rot_tangle} * {formula_x_rot_tangle}))"
 formula_exit_angle_horz = f"arctan2({formula_x_rot_tangle}, ({formula_z_rot_tangle}))"
 formula_exit_angle = formula_scattering_angle_vert
-formula_exit_angle_horz = formula_scattering_angle_horz
 
 formula_qbeam_lab = f"2.0e-9/λ*π*(cos({formula_scattering_angle_vert})*cos({formula_scattering_angle_horz}) - 1)"
 formula_qhorz_lab = f"2.0e-9/λ*π*cos({formula_scattering_angle_vert})*sin({formula_scattering_angle_horz})"