diff --git a/crates/fj-math/src/transform.rs b/crates/fj-math/src/transform.rs
index b25be9c9a..2fbd7a6eb 100644
--- a/crates/fj-math/src/transform.rs
+++ b/crates/fj-math/src/transform.rs
@@ -53,6 +53,12 @@ impl Transform {
         Vector::from([d[0], d[1], d[2]])
     }
 
+    /// # Extract the "up" vector from the rotational component
+    pub fn up(&self) -> Vector<3> {
+        let d = self.data();
+        Vector::from([d[4], d[5], d[6]])
+    }
+
     /// Transform the given point
     pub fn transform_point(&self, point: &Point<3>) -> Point<3> {
         Point::from(self.0.transform_point(&point.to_na()))
diff --git a/crates/fj-viewer/src/input/rotation.rs b/crates/fj-viewer/src/input/rotation.rs
index 6263c3312..4a76fb22f 100644
--- a/crates/fj-viewer/src/input/rotation.rs
+++ b/crates/fj-viewer/src/input/rotation.rs
@@ -1,4 +1,4 @@
-use fj_math::{Transform, Vector};
+use fj_math::Transform;
 
 use crate::camera::{Camera, FocusPoint};
 
@@ -15,7 +15,7 @@ impl Rotation {
 
         // the model rotates not the camera, so invert the transform
         let camera_rotation = camera.rotation.inverse();
-        let up_vector = up_vector(&camera_rotation);
+        let up_vector = camera_rotation.up();
 
         let rotation = Transform::rotation(camera_rotation.right() * angle_x)
             * Transform::rotation(up_vector * angle_y);
@@ -29,8 +29,3 @@ impl Rotation {
         camera.translation = transform.extract_translation();
     }
 }
-
-fn up_vector(rotation: &Transform) -> Vector<3> {
-    let d = rotation.data();
-    Vector::from([d[4], d[5], d[6]])
-}