diff --git a/ddd/src/main/java/com/baeldung/ddd/layers/domain/Order.java b/ddd/src/main/java/com/baeldung/ddd/layers/domain/Order.java
index 369f860bae..6306138100 100644
--- a/ddd/src/main/java/com/baeldung/ddd/layers/domain/Order.java
+++ b/ddd/src/main/java/com/baeldung/ddd/layers/domain/Order.java
@@ -76,6 +76,6 @@ public class Order {
     }
 
     public List<OrderItem> getOrderItems() {
-        return orderItems;
+        return Collections.unmodifiableList(orderItems);
     }
 }