diff --git a/bapsf_motion/transform/lapd_droop.py b/bapsf_motion/transform/lapd_droop.py
index 5a604a45..6abd934a 100644
--- a/bapsf_motion/transform/lapd_droop.py
+++ b/bapsf_motion/transform/lapd_droop.py
@@ -483,7 +483,7 @@ def _convert_to_droop_points(self, points: np.ndarray) -> np.ndarray:
         #    - rt => (radius, theta)
         points_rt = np.empty_like(_points)
         points_rt[..., 0] = np.linalg.norm(_points, axis=1) + self.pivot_to_feedthru
-        points_rt[..., 1] = np.tan(_points[..., 1] / _points[..., 0])
+        points_rt[..., 1] = np.arctan(_points[..., 1] / _points[..., 0])
 
         # Calculate dx and dy of the droop
         #    - delta will always be negative in the ball valve coords