diff --git a/web/Light9CursorCanvas.ts b/web/Light9CursorCanvas.ts
--- a/web/Light9CursorCanvas.ts
+++ b/web/Light9CursorCanvas.ts
@@ -3,6 +3,7 @@ import { css, html, LitElement, Property
 import { customElement, property } from "lit/decorators.js";
 import Sylvester from "sylvester";
 import { line } from "./drawing";
+import { Vector } from "./lib/sylvester";
 
 const $V = Sylvester.Vector.create;