diff --git a/src/Viewer.ts b/src/Viewer.ts
index 7fbdd40..e6d0107 100644
--- a/src/Viewer.ts
+++ b/src/Viewer.ts
@@ -214,6 +214,7 @@ export class Viewer
         {
           if (obj.id == meshId)
           {
+            this.oldMesh = obj;
             obj.material = selectMaterial;
             this.m_bNeedUpdate = true;
           }