diff --git a/app/src/processing/app/AbstractMonitor.java b/app/src/processing/app/AbstractMonitor.java
index 4394ca964..9a3de6043 100644
--- a/app/src/processing/app/AbstractMonitor.java
+++ b/app/src/processing/app/AbstractMonitor.java
@@ -14,6 +14,7 @@ import java.awt.event.WindowEvent;
 
 import static processing.app.I18n._;
 
+@SuppressWarnings("serial")
 public abstract class AbstractMonitor extends JFrame implements MessageConsumer {
 
   protected final JLabel noLineEndingAlert;
diff --git a/app/src/processing/app/LastUndoableEditAwareUndoManager.java b/app/src/processing/app/LastUndoableEditAwareUndoManager.java
index 336cfe15f..0cd678a93 100644
--- a/app/src/processing/app/LastUndoableEditAwareUndoManager.java
+++ b/app/src/processing/app/LastUndoableEditAwareUndoManager.java
@@ -5,6 +5,7 @@ import javax.swing.undo.CannotUndoException;
 import javax.swing.undo.UndoManager;
 import javax.swing.undo.UndoableEdit;
 
+@SuppressWarnings("serial")
 public class LastUndoableEditAwareUndoManager extends UndoManager {
 
   private UndoableEdit lastUndoableEdit;
diff --git a/app/src/processing/app/NetworkMonitor.java b/app/src/processing/app/NetworkMonitor.java
index 73a973aad..5f89382ac 100644
--- a/app/src/processing/app/NetworkMonitor.java
+++ b/app/src/processing/app/NetworkMonitor.java
@@ -28,7 +28,6 @@ public class NetworkMonitor extends AbstractMonitor {
   private MessageSiphon inputConsumer;
   private Session session;
   private Channel channel;
-  private MessageSiphon errorConsumer;
   private int connectionAttempts;
 
   public NetworkMonitor(BoardPort port, Base base) {
@@ -98,7 +97,7 @@ public class NetworkMonitor extends AbstractMonitor {
     channel.connect();
 
     inputConsumer = new MessageSiphon(inputStream, this);
-    errorConsumer = new MessageSiphon(errStream, this);
+    new MessageSiphon(errStream, this);
 
     if (connectionAttempts > 1) {
       SwingUtilities.invokeLater(new Runnable() {
diff --git a/app/src/processing/app/SerialException.java b/app/src/processing/app/SerialException.java
index d47e60189..7fbc3e7ad 100644
--- a/app/src/processing/app/SerialException.java
+++ b/app/src/processing/app/SerialException.java
@@ -22,6 +22,7 @@ package processing.app;
 
 import java.io.IOException;
 
+@SuppressWarnings("serial")
 public class SerialException extends IOException {
   public SerialException() {
     super();
diff --git a/app/src/processing/app/SerialMonitor.java b/app/src/processing/app/SerialMonitor.java
index 49e7006a3..0be575ed2 100644
--- a/app/src/processing/app/SerialMonitor.java
+++ b/app/src/processing/app/SerialMonitor.java
@@ -27,6 +27,7 @@ import java.awt.event.ActionListener;
 
 import static processing.app.I18n._;
 
+@SuppressWarnings("serial")
 public class SerialMonitor extends AbstractMonitor {
 
   private final String port;
diff --git a/app/src/processing/app/SerialNotFoundException.java b/app/src/processing/app/SerialNotFoundException.java
index a3ab755b8..d8660c110 100644
--- a/app/src/processing/app/SerialNotFoundException.java
+++ b/app/src/processing/app/SerialNotFoundException.java
@@ -1,5 +1,3 @@
-/* -*- mode: jde; c-basic-offset: 2; indent-tabs-mode: nil -*- */
-
 /*
   Copyright (c) 2007 David A. Mellis
 
@@ -20,6 +18,7 @@
 
 package processing.app;
 
+@SuppressWarnings("serial")
 public class SerialNotFoundException extends SerialException {
   public SerialNotFoundException() {
     super();