diff --git a/packages/model3d-viewer/src/scene.ts b/packages/model3d-viewer/src/scene.ts
index bfc11ce3e..24d323b71 100644
--- a/packages/model3d-viewer/src/scene.ts
+++ b/packages/model3d-viewer/src/scene.ts
@@ -48,11 +48,12 @@ export function disposeModel3dViewerObject(object: ThreeTypes.Object3D) {
     const mesh = child as ThreeTypes.Mesh;
     mesh.geometry?.dispose?.();
     const material = mesh.material;
-    const materials = Array.isArray(material)
-      ? material
-      : material
-        ? [material]
-        : [];
+    let materials: ThreeTypes.Material[] = [];
+    if (Array.isArray(material)) {
+      materials = material;
+    } else if (material) {
+      materials = [material];
+    }
     for (const entry of materials) {
       for (const value of Object.values(
         entry as unknown as Record<string, unknown>,