diff --git a/1-js/09-classes/04-private-protected-properties-methods/article.md b/1-js/09-classes/04-private-protected-properties-methods/article.md
index 4396358d5..90ec94dee 100644
--- a/1-js/09-classes/04-private-protected-properties-methods/article.md
+++ b/1-js/09-classes/04-private-protected-properties-methods/article.md
@@ -163,6 +163,7 @@ class CoffeeMachine {
   *!*setWaterAmount(value)*/!* {
     if (value < 0) value = 0;
     this._waterAmount = value;
+    return this;
   }
 
   *!*getWaterAmount()*/!* {