diff --git a/topola/src/layout.rs b/topola/src/layout.rs
index 3afaec2..95b221c 100644
--- a/topola/src/layout.rs
+++ b/topola/src/layout.rs
@@ -147,15 +147,8 @@ impl Layout {
     where
         F: FnOnce(&mut JointSpec),
     {
-        let old_joint = self.joints.get(&id.index()).unwrap();
-        self.joints_rtree
-            .remove(&GeomWithData::new(old_joint.bbox(), id));
-
-        self.joints.modify(id.index(), |joint| f(&mut joint.spec));
-
+        self.modify_joint_raw(id, |joint| f(&mut joint.spec));
         let new_joint = self.joints.get(&id.index()).unwrap().clone();
-        self.joints_rtree
-            .insert(GeomWithData::new(new_joint.bbox(), id), ());
 
         for &segment in &new_joint.segments {
             self.update_segment(segment);
@@ -166,6 +159,21 @@ impl Layout {
         }
     }
 
+    fn modify_joint_raw<F>(&mut self, id: JointId, f: F)
+    where
+        F: FnOnce(&mut Joint),
+    {
+        let old_joint = self.joints.get(&id.index()).unwrap();
+        self.joints_rtree
+            .remove(&GeomWithData::new(old_joint.bbox(), id));
+
+        self.joints.modify(id.index(), |joint| f(joint));
+
+        let new_joint = self.joints.get(&id.index()).unwrap().clone();
+        self.joints_rtree
+            .insert(GeomWithData::new(new_joint.bbox(), id), ());
+    }
+
     pub fn add_segment(&mut self, spec: SegmentSpec) -> SegmentId {
         self.add_segment_raw(Segment {
             spec,