diff --git a/src/document/scene-document-validation.js b/src/document/scene-document-validation.js
index d485393e..56c8e052 100644
--- a/src/document/scene-document-validation.js
+++ b/src/document/scene-document-validation.js
@@ -2,7 +2,7 @@ import {} from "../assets/project-assets";
 import { isModelInstanceCollisionMode } from "../assets/model-instances";
 import { isPlayerStartColliderMode, getPlayerStartColliderHeight } from "../entities/entity-instances";
 import {} from "../interactions/interaction-links";
-import { BOX_FACE_IDS, hasPositiveBoxSize } from "./brushes";
+import { BOX_FACE_IDS, BOX_VERTEX_IDS, hasPositiveBoxSize } from "./brushes";
 import { isAdvancedRenderingShadowMapSize, isAdvancedRenderingShadowType, isAdvancedRenderingToneMappingMode, isHexColorString } from "./world-settings";
 export function createDiagnostic(severity, code, message, path, scope = "document") {
     return {
@@ -557,6 +557,11 @@ export function validateSceneDocument(document) {
         if (!isFiniteVec3(brush.size) || !hasPositiveBoxSize(brush.size)) {
             diagnostics.push(createDiagnostic("error", "invalid-box-size", "Box brush sizes must remain finite and positive on every axis.", `${path}.size`));
         }
+        for (const vertexId of BOX_VERTEX_IDS) {
+            if (!isFiniteVec3(brush.geometry.vertices[vertexId])) {
+                diagnostics.push(createDiagnostic("error", "invalid-box-geometry-vertex", "Box brush geometry vertices must remain finite on every axis.", `${path}.geometry.vertices.${vertexId}`));
+            }
+        }
         for (const faceId of BOX_FACE_IDS) {
             const materialId = brush.faces[faceId].materialId;
             if (materialId !== null && document.materials[materialId] === undefined) {
diff --git a/src/runtime-three/rapier-collision-world.js b/src/runtime-three/rapier-collision-world.js
index 8df42b7c..1cef7014 100644
--- a/src/runtime-three/rapier-collision-world.js
+++ b/src/runtime-three/rapier-collision-world.js
@@ -56,12 +56,7 @@ function attachBrushCollider(world, collider) {
     const body = world.createRigidBody(RAPIER.RigidBodyDesc.fixed()
         .setTranslation(collider.center.x, collider.center.y, collider.center.z)
         .setRotation(createRapierQuaternion(collider.rotationDegrees)));
-    const halfExtents = {
-        x: collider.size.x * 0.5,
-        y: collider.size.y * 0.5,
-        z: collider.size.z * 0.5
-    };
-    world.createCollider(RAPIER.ColliderDesc.cuboid(halfExtents.x, halfExtents.y, halfExtents.z), body);
+    world.createCollider(RAPIER.ColliderDesc.trimesh(collider.vertices, collider.indices), body);
 }
 function attachSimpleModelCollider(world, collider) {
     const body = createFixedBodyForModelCollider(world, collider);