diff --git a/crates/fj-core/src/geometry/geometry.rs b/crates/fj-core/src/geometry/geometry.rs
index 9b5a199bf..c10f124d2 100644
--- a/crates/fj-core/src/geometry/geometry.rs
+++ b/crates/fj-core/src/geometry/geometry.rs
@@ -1,4 +1,4 @@
-use std::{collections::BTreeMap, rc::Rc};
+use std::collections::BTreeMap;
 
 use fj_math::Vector;
 
@@ -71,7 +71,7 @@ impl Geometry {
         self_.define_surface_inner_2(
             self_.xy_plane.clone(),
             SurfaceGeom {
-                geometry: Rc::new(SweptCurve {
+                geometry: Box::new(SweptCurve {
                     u: Path::x_axis(),
                     v: Vector::unit_y(),
                 }),
@@ -80,7 +80,7 @@ impl Geometry {
         self_.define_surface_inner_2(
             self_.xz_plane.clone(),
             SurfaceGeom {
-                geometry: Rc::new(SweptCurve {
+                geometry: Box::new(SweptCurve {
                     u: Path::x_axis(),
                     v: Vector::unit_z(),
                 }),
@@ -89,7 +89,7 @@ impl Geometry {
         self_.define_surface_inner_2(
             self_.yz_plane.clone(),
             SurfaceGeom {
-                geometry: Rc::new(SweptCurve {
+                geometry: Box::new(SweptCurve {
                     u: Path::y_axis(),
                     v: Vector::unit_z(),
                 }),
@@ -310,5 +310,5 @@ pub enum CurveGeom2 {
 /// representation.
 pub struct SurfaceGeom {
     /// # The geometric representation of the surface
-    pub geometry: Rc<dyn GenTriMesh>,
+    pub geometry: Box<dyn GenTriMesh>,
 }
diff --git a/crates/fj-core/src/operations/build/surface.rs b/crates/fj-core/src/operations/build/surface.rs
index 9c88c5792..36e41e6bb 100644
--- a/crates/fj-core/src/operations/build/surface.rs
+++ b/crates/fj-core/src/operations/build/surface.rs
@@ -1,5 +1,3 @@
-use std::rc::Rc;
-
 use fj_math::{Point, Scalar, Vector};
 
 use crate::{
@@ -29,7 +27,7 @@ pub trait BuildSurface {
         core.layers.geometry.define_surface_2(
             surface.clone(),
             SurfaceGeom {
-                geometry: Rc::new(surface_geom),
+                geometry: Box::new(surface_geom),
             },
         );
 
diff --git a/crates/fj-core/src/operations/transform/surface.rs b/crates/fj-core/src/operations/transform/surface.rs
index eec5e15d2..c7bbe663a 100644
--- a/crates/fj-core/src/operations/transform/surface.rs
+++ b/crates/fj-core/src/operations/transform/surface.rs
@@ -1,5 +1,3 @@
-use std::rc::Rc;
-
 use fj_math::Transform;
 
 use crate::{
@@ -45,7 +43,7 @@ impl TransformObject for &Handle<Surface> {
                 core.layers.geometry.define_surface_2(
                     surface.clone(),
                     SurfaceGeom {
-                        geometry: Rc::new(TransformedSurface {
+                        geometry: Box::new(TransformedSurface {
                             surface: self.clone(),
                             transform: *transform,
                         }),