diff --git a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/ESBButton.java b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/ESBButton.java
index 2214dce69..a16207c72 100644
--- a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/ESBButton.java
+++ b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/ESBButton.java
@@ -41,9 +41,9 @@ import org.contikios.cooja.mspmote.ESBMote;
  */
 @ClassDescription("Button")
 public class ESBButton extends Button {
-  private static Logger logger = Logger.getLogger(ESBButton.class);
+  private static final Logger logger = Logger.getLogger(ESBButton.class);
 
-  private ESBMote mote;
+  private final ESBMote mote;
 
   public ESBButton(Mote mote) {
     super(mote);
diff --git a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspButton.java b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspButton.java
index 30214802a..459205153 100644
--- a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspButton.java
+++ b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspButton.java
@@ -31,7 +31,6 @@ package org.contikios.cooja.mspmote.interfaces;
 import org.contikios.cooja.ClassDescription;
 import org.contikios.cooja.Mote;
 import org.contikios.cooja.Simulation;
-import org.contikios.cooja.TimeEvent;
 import org.contikios.cooja.interfaces.Button;
 import org.contikios.cooja.mspmote.MspMote;
 
diff --git a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/SkyButton.java b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/SkyButton.java
index 502e75570..e20376a69 100644
--- a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/SkyButton.java
+++ b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/SkyButton.java
@@ -38,9 +38,9 @@ import org.contikios.cooja.mspmote.SkyMote;
 
 @ClassDescription("Button")
 public class SkyButton extends Button {
-  private static Logger logger = Logger.getLogger(SkyButton.class);
+  private static final Logger logger = Logger.getLogger(SkyButton.class);
 
-  private SkyMote skyMote;
+  private final SkyMote skyMote;
 
   public SkyButton(Mote mote) {
     super(mote);
diff --git a/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiButton.java b/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiButton.java
index dea5728a3..f4cc75acd 100644
--- a/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiButton.java
+++ b/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiButton.java
@@ -59,10 +59,10 @@ import org.contikios.cooja.mote.memory.VarMemory;
  * @author Fredrik Osterlind
  */
 public class ContikiButton extends Button implements ContikiMoteInterface {
-  private VarMemory moteMem;
-  private ContikiMote mote;
+  private final VarMemory moteMem;
+  private final ContikiMote mote;
 
-  private static Logger logger = Logger.getLogger(ContikiButton.class);
+  private static final Logger logger = Logger.getLogger(ContikiButton.class);
 
   /**
    * Creates an interface to the button at mote.
diff --git a/tools/cooja/java/org/contikios/cooja/interfaces/Button.java b/tools/cooja/java/org/contikios/cooja/interfaces/Button.java
index 62e7a5eb0..f04b81e8b 100644
--- a/tools/cooja/java/org/contikios/cooja/interfaces/Button.java
+++ b/tools/cooja/java/org/contikios/cooja/interfaces/Button.java
@@ -36,7 +36,6 @@ import java.util.Collection;
 import javax.swing.JButton;
 import javax.swing.JPanel;
 import org.contikios.cooja.*;
-import org.contikios.cooja.mspmote.SkyMote;
 import org.jdom.Element;
 
 /**