diff --git a/1_preprocessing/gtAcqGetPhiStep.m b/1_preprocessing/gtAcqGetPhiStep.m
index 84b0b5907d80230be2c038389bd3ad3d63f7e86f..860edd97ecadebae2c2c1a68337eb006ec03f50e 100644
--- a/1_preprocessing/gtAcqGetPhiStep.m
+++ b/1_preprocessing/gtAcqGetPhiStep.m
@@ -28,6 +28,6 @@ function phi_step = get_step(parameters, det_ind)
     else
         range_basetilt = parameters.acq(det_ind).range_basetilt(2) - parameters.acq(det_ind).range_basetilt(1);
         num_basetilt_imgs = parameters.acq(det_ind).nproj_basetilt;
-        phi_step = range_basetilt / (num_basetilt_imgs - 1);
+        phi_step = range_basetilt / num_basetilt_imgs;
     end
 end