diff --git a/smack-core/src/main/java/org/jivesoftware/smack/packet/Message.java b/smack-core/src/main/java/org/jivesoftware/smack/packet/Message.java
index f31b3ca28..4cf3596c5 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/packet/Message.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/packet/Message.java
@@ -480,8 +480,8 @@ public final class Message extends Packet {
      */
     public static class Subject {
 
-        private String subject;
-        private String language;
+        private final String subject;
+        private final String language;
 
         private Subject(String language, String subject) {
             if (language == null) {
@@ -543,8 +543,8 @@ public final class Message extends Packet {
      */
     public static class Body {
 
-        private String message;
-        private String language;
+        private final String message;
+        private final String language;
 
         private Body(String language, String message) {
             if (language == null) {
diff --git a/smack-core/src/main/java/org/jivesoftware/smack/packet/Packet.java b/smack-core/src/main/java/org/jivesoftware/smack/packet/Packet.java
index c14b3527c..7091ac71d 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/packet/Packet.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/packet/Packet.java
@@ -48,13 +48,13 @@ public abstract class Packet extends TopLevelStreamElement {
     /**
      * A prefix helps to make sure that ID's are unique across multiple instances.
      */
-    private static String prefix = StringUtils.randomString(5) + "-";
+    private static final String prefix = StringUtils.randomString(5) + "-";
 
     /**
      * Keeps track of the current increment, which is appended to the prefix to
      * forum a unique ID.
      */
-    private static AtomicLong id = new AtomicLong();
+    private static final AtomicLong id = new AtomicLong();
 
     private final Map<String, PacketExtension> packetExtensions = new HashMap<String, PacketExtension>(12);