diff --git a/src/main/java/com/jenkov/nioserver/Message.java b/src/main/java/com/jenkov/nioserver/Message.java
index d11579a..9c91351 100644
--- a/src/main/java/com/jenkov/nioserver/Message.java
+++ b/src/main/java/com/jenkov/nioserver/Message.java
@@ -94,6 +94,7 @@ public void writePartialMessageToMessage(Message message, int endIndex){
         int lengthOfPartialMessage     = (message.offset + message.length) - endIndex;
 
         System.arraycopy(message.sharedArray, startIndexOfPartialMessage, this.sharedArray, this.offset, lengthOfPartialMessage);
+        this.length=this.length+lengthOfPartialMessage;
     }
 
     public int writeToByteBuffer(ByteBuffer byteBuffer){