diff --git a/core/src/main/java/org/springframework/ws/transport/context/DefaultTransportContext.java b/core/src/main/java/org/springframework/ws/transport/context/DefaultTransportContext.java
index 6626ca1c..edfc7a6c 100644
--- a/core/src/main/java/org/springframework/ws/transport/context/DefaultTransportContext.java
+++ b/core/src/main/java/org/springframework/ws/transport/context/DefaultTransportContext.java
@@ -16,6 +16,7 @@
 
 package org.springframework.ws.transport.context;
 
+import org.springframework.util.Assert;
 import org.springframework.ws.transport.WebServiceConnection;
 
 /**
@@ -30,6 +31,7 @@ public class DefaultTransportContext implements TransportContext {
 
     /** Creates a new <code>DefaultTransportContext</code> that exposes the given connection. */
     public DefaultTransportContext(WebServiceConnection connection) {
+        Assert.notNull(connection, "'connection' must not be null");
         this.connection = connection;
     }
 
@@ -37,4 +39,7 @@ public class DefaultTransportContext implements TransportContext {
         return connection;
     }
 
+    public String toString() {
+        return connection.toString();
+    }
 }
diff --git a/core/src/main/java/org/springframework/ws/transport/context/TransportContextHolder.java b/core/src/main/java/org/springframework/ws/transport/context/TransportContextHolder.java
index c01abb99..3deccd6b 100644
--- a/core/src/main/java/org/springframework/ws/transport/context/TransportContextHolder.java
+++ b/core/src/main/java/org/springframework/ws/transport/context/TransportContextHolder.java
@@ -25,7 +25,7 @@ package org.springframework.ws.transport.context;
  */
 public abstract class TransportContextHolder {
 
-    private static final ThreadLocal transportContextHolder = new ThreadLocal();
+    private static final ThreadLocal transportContextHolder = new TransportThreadLocal();
 
     /**
      * Associate the given <code>TransportContext</code> with the current thread.
@@ -44,4 +44,11 @@ public abstract class TransportContextHolder {
     public static TransportContext getTransportContext() {
         return (TransportContext) transportContextHolder.get();
     }
+
+    private static class TransportThreadLocal extends ThreadLocal {
+
+        public String toString() {
+            return "Transport State";
+        }
+    }
 }