diff --git a/src/mesh/tool.js b/src/mesh/tool.js
index 73e0d687..41db2f8b 100644
--- a/src/mesh/tool.js
+++ b/src/mesh/tool.js
@@ -3,6 +3,7 @@
 import { THREE } from '../ext/three.js';
 const { Vector3 } = THREE;
 import { geom } from './geom.js';
+import earcut from '../ext/earcut.js';
 
 const empty = 0xffffffff;