diff --git a/src/spacetime/arm.rs b/src/spacetime/arm.rs
index b2cd6da..37c7b90 100644
--- a/src/spacetime/arm.rs
+++ b/src/spacetime/arm.rs
@@ -464,7 +464,7 @@ impl Arm{
 
     fn __update_fixed_ro(&mut self, i: usize) {
         self.out_positions[i + 1] = self.out_rot_quats[i] * self.displacements[i] + self.out_positions[i];
-        self.out_rot_quats[i + 1] = self.out_rot_quats[i] * self.rot_offset_quats[i];
+        self.out_rot_quats[i + 1] = self.out_rot_quats[i] * self.rot_offset_quats[i+1];
         self.out_rot_mats[i + 1] = *self.out_rot_quats[i].to_rotation_matrix().matrix();
     }
 }
@@ -661,4 +661,4 @@ fn get_fixed_closure(axis: &String, rot_offset_matrix: &nalgebra::Matrix3<f64>,
 fn get_prismatic_closure(axis: &String, rot_offset_matrix: &nalgebra::Matrix3<f64>, disp: &nalgebra::Vector3<f64>, do_rot_offset: bool) {
 
 }
-*/
\ No newline at end of file
+*/