diff --git a/src/main/java/com/hivemq/codec/decoder/MQTTMessageDecoder.java b/src/main/java/com/hivemq/codec/decoder/MQTTMessageDecoder.java
index 292657849..110e1ce01 100644
--- a/src/main/java/com/hivemq/codec/decoder/MQTTMessageDecoder.java
+++ b/src/main/java/com/hivemq/codec/decoder/MQTTMessageDecoder.java
@@ -207,7 +207,7 @@ private static boolean isAlreadyConnected(ClientConnectionContext clientConnecti
         return clientConnectionContext.getProtocolVersion() != null;
     }
 
-    private Message handledMessage(
+    private @Nullable Message handledMessage(
             final @NotNull ByteBuf buf,
             final @NotNull ClientConnectionContext clientConnectionContext,
             final byte fixedHeader,