1 files changed, 1 insertions, 1 deletions
diff --git a/src/main/java/org/traccar/handler/AcknowledgementHandler.java b/src/main/java/org/traccar/handler/AcknowledgementHandler.java
index c3f6038de..4c1085998 100644
--- a/src/main/java/org/traccar/handler/AcknowledgementHandler.java
+++ b/src/main/java/org/traccar/handler/AcknowledgementHandler.java
@@ -61,7 +61,7 @@ public class AcknowledgementHandler extends ChannelOutboundHandlerAdapter {
         }
     }
 
-    private static class Entry {
+    private static final class Entry {
         private final Object message;
         private final ChannelPromise promise;