diff --git a/leshan-client-core/src/main/java/org/eclipse/leshan/client/observer/LwM2mClientObserverDispatcher.java b/leshan-client-core/src/main/java/org/eclipse/leshan/client/observer/LwM2mClientObserverDispatcher.java
index 0c0eaa93b5..d5576bc503 100644
--- a/leshan-client-core/src/main/java/org/eclipse/leshan/client/observer/LwM2mClientObserverDispatcher.java
+++ b/leshan-client-core/src/main/java/org/eclipse/leshan/client/observer/LwM2mClientObserverDispatcher.java
@@ -25,7 +25,7 @@
  *
  */
 public class LwM2mClientObserverDispatcher implements LwM2mClientObserver2 {
-    protected CopyOnWriteArrayList<LwM2mClientObserver> observers = new CopyOnWriteArrayList<>();
+    private CopyOnWriteArrayList<LwM2mClientObserver> observers = new CopyOnWriteArrayList<>();
 
     public void addObserver(LwM2mClientObserver observer) {
         observers.add(observer);