diff --git a/classes-es6/demo.js b/classes-es6/demo.js
index 7340dce214..e98aa2c819 100644
--- a/classes-es6/demo.js
+++ b/classes-es6/demo.js
@@ -77,7 +77,7 @@ class Square extends Polygon {
   }
 
   set area(value) {
-    this.area = value;
+    this._area = value;
   }
 }