diff --git a/web/app/canvas.js b/web/app/canvas.js
index 54366aa2..bf973309 100644
--- a/web/app/canvas.js
+++ b/web/app/canvas.js
@@ -300,6 +300,7 @@ TCAD.TWO.SketchObject.prototype.draw = function(ctx, scale) {
 };
 
 TCAD.TWO.Ref = function() {
+  this.id = TCAD.TWO.utils.genID();
   this.value = 0;
 };