diff --git a/src/test/java/net/kemitix/wiser/assertions/AbstractWiserTest.java b/src/test/java/net/kemitix/wiser/assertions/AbstractWiserTest.java
index cea04a6..7f7121f 100644
--- a/src/test/java/net/kemitix/wiser/assertions/AbstractWiserTest.java
+++ b/src/test/java/net/kemitix/wiser/assertions/AbstractWiserTest.java
@@ -4,40 +4,33 @@ import org.junit.After;
 import org.junit.Before;
 import org.subethamail.wiser.Wiser;
 
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
 import java.util.Properties;
 
 import javax.mail.Session;
 
-/**
- * Abstract base class for wiser tests.
- *
- * @author pcampbell
- */
-public abstract class AbstractWiserTest {
+abstract class AbstractWiserTest {
 
-    /**
-     * Test mail server port.
-     */
-    protected static final int PORT = 12345;
+    private int port;
 
-    /**
-     * Test mail server.
-     */
     private Wiser wiser;
 
-    /**
-     * Prepare each test.
-     */
     @Before
-    @SuppressWarnings("magicnumber")
-    public void setUp() {
-        wiser = new Wiser(PORT);
+    public void setUp() throws IOException {
+        port = findFreePort();
+        wiser = new Wiser(port);
         wiser.start();
     }
 
-    /**
-     * Clean up after each test.
-     */
+    private int findFreePort() throws IOException {
+        try(final ServerSocket serverSocket = new ServerSocket()) {
+            serverSocket.bind(new InetSocketAddress(0));
+            return serverSocket.getLocalPort();
+        }
+    }
+
     @After
     public void tearDown() {
         wiser.stop();
@@ -56,9 +49,16 @@ public abstract class AbstractWiserTest {
         Properties properties = new Properties();
         properties.setProperty("mail.transport.protocol", "smtp");
         properties.setProperty("mail.smtp.host", "localhost");
-        properties.setProperty("mail.smtp.port", "" + PORT);
-        Session session = Session.getInstance(properties);
-        return session;
+        properties.setProperty("mail.smtp.port", "" + port);
+        return Session.getInstance(properties);
     }
 
+    /**
+     * The test mail server port.
+     *
+     * @return the port he test mail server is running on
+     */
+    protected int getPort() {
+        return port;
+    }
 }
diff --git a/src/test/java/net/kemitix/wiser/assertions/Issue6Test.java b/src/test/java/net/kemitix/wiser/assertions/Issue6Test.java
index 72296a8..61ae67c 100644
--- a/src/test/java/net/kemitix/wiser/assertions/Issue6Test.java
+++ b/src/test/java/net/kemitix/wiser/assertions/Issue6Test.java
@@ -26,7 +26,7 @@ public class Issue6Test extends AbstractWiserTest {
         message.setSubject("Subject");
         message.setText("Hi Carl,\n\nA new message was just posted.");
         final JavaMailSenderImpl sender = new JavaMailSenderImpl();
-        sender.setPort(PORT);
+        sender.setPort(getPort());
         //when
         sender.send(message);
         //then
diff --git a/src/test/java/net/kemitix/wiser/assertions/WiserAssertionsTest.java b/src/test/java/net/kemitix/wiser/assertions/WiserAssertionsTest.java
index 83d52f1..0928425 100644
--- a/src/test/java/net/kemitix/wiser/assertions/WiserAssertionsTest.java
+++ b/src/test/java/net/kemitix/wiser/assertions/WiserAssertionsTest.java
@@ -25,9 +25,6 @@ import javax.mail.internet.MimeMultipart;
  */
 public class WiserAssertionsTest extends AbstractWiserTest {
 
-    /**
-     * Logger.
-     */
     private static final Logger LOG
             = Logger.getLogger(WiserAssertionsTest.class.getName());