diff --git a/build.gradle b/build.gradle
index 90347de..f3265c7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -55,7 +55,7 @@ ospackage {
 
 buildRpm {
     dependsOn startShadowScripts
-    os = LINUX
+    os = "LINUX"
 }
 
 buildDeb {
diff --git a/src/main/java/biz/nellemann/syslogd/Facility.java b/src/main/java/biz/nellemann/syslogd/Facility.java
index 9b4107b..001a7c4 100644
--- a/src/main/java/biz/nellemann/syslogd/Facility.java
+++ b/src/main/java/biz/nellemann/syslogd/Facility.java
@@ -72,7 +72,7 @@ public enum Facility {
         return this.facilityNumber;
     }
 
-    private Integer facilityNumber;
+    private final Integer facilityNumber;
     Facility(int facilityNumber) {
         this.facilityNumber = facilityNumber;
     }
diff --git a/src/main/java/biz/nellemann/syslogd/Severity.java b/src/main/java/biz/nellemann/syslogd/Severity.java
index ffb9a5d..4364afb 100644
--- a/src/main/java/biz/nellemann/syslogd/Severity.java
+++ b/src/main/java/biz/nellemann/syslogd/Severity.java
@@ -40,7 +40,7 @@ public enum Severity {
         return this.severityNumber;
     }
 
-    private Integer severityNumber;
+    private final Integer severityNumber;
     Severity(int severityNumber) {
         this.severityNumber = severityNumber;
     }
diff --git a/src/main/java/biz/nellemann/syslogd/TcpServer.java b/src/main/java/biz/nellemann/syslogd/TcpServer.java
index 24bdc44..aca61ee 100644
--- a/src/main/java/biz/nellemann/syslogd/TcpServer.java
+++ b/src/main/java/biz/nellemann/syslogd/TcpServer.java
@@ -26,7 +26,7 @@ import java.util.List;
 
 public class TcpServer {
 
-    private int port;
+    private final int port;
     private ServerSocket serverSocket;
 
     TcpServer() {
@@ -52,7 +52,7 @@ public class TcpServer {
      * Event Listener Configuration
      */
 
-    protected List<LogListener> eventListeners = new ArrayList<>();
+    protected final List<LogListener> eventListeners = new ArrayList<>();
 
     public synchronized void addEventListener( LogListener l ) {
         eventListeners.add( l );
@@ -66,9 +66,9 @@ public class TcpServer {
 
     private static class ClientHandler extends Thread {
 
-        protected List<LogListener> eventListeners;
+        protected final List<LogListener> eventListeners;
 
-        private Socket clientSocket;
+        private final Socket clientSocket;
         private BufferedReader in;
 
         public ClientHandler(Socket socket, List<LogListener> eventListeners) {
diff --git a/src/main/java/biz/nellemann/syslogd/UdpServer.java b/src/main/java/biz/nellemann/syslogd/UdpServer.java
index 0b78379..3383003 100644
--- a/src/main/java/biz/nellemann/syslogd/UdpServer.java
+++ b/src/main/java/biz/nellemann/syslogd/UdpServer.java
@@ -18,13 +18,14 @@ package biz.nellemann.syslogd;
 import java.io.IOException;
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
 public class UdpServer extends Thread {
 
-    protected DatagramSocket socket = null;
+    protected DatagramSocket socket;
     protected boolean listen = true;
 
     public UdpServer() throws IOException {
@@ -44,7 +45,7 @@ public class UdpServer extends Thread {
         while (listen) {
             try {
                 socket.receive(packet);
-                String packetData = new String(packet.getData(), packet.getOffset(), packet.getLength(), "UTF8");
+                String packetData = new String(packet.getData(), packet.getOffset(), packet.getLength(), StandardCharsets.UTF_8);
                 sendEvent(packetData);
             } catch (Exception e) {
                 e.printStackTrace();