diff --git a/test/src/main/java/org/springframework/ws/mock/client/MockWebServiceMessageSender.java b/test/src/main/java/org/springframework/ws/mock/client/MockWebServiceMessageSender.java
index caf6da5f..563814a9 100644
--- a/test/src/main/java/org/springframework/ws/mock/client/MockWebServiceMessageSender.java
+++ b/test/src/main/java/org/springframework/ws/mock/client/MockWebServiceMessageSender.java
@@ -25,8 +25,14 @@ import java.util.List;
 import org.springframework.util.Assert;
 import org.springframework.ws.transport.WebServiceMessageSender;
 
-import static org.junit.Assert.assertTrue;
-
+/**
+ * Mock implementation of {@link WebServiceMessageSender}. Contains a list of expected {@link MockSenderConnection}s,
+ * and iterates over those.
+ *
+ * @author Arjen Poutsma
+ * @author Lukas Krecan
+ * @since 2.0
+ */
 class MockWebServiceMessageSender implements WebServiceMessageSender {
 
     private final List<MockSenderConnection> expectedConnections = new LinkedList<MockSenderConnection>();
@@ -38,7 +44,9 @@ class MockWebServiceMessageSender implements WebServiceMessageSender {
         if (connectionIterator == null) {
             connectionIterator = expectedConnections.iterator();
         }
-        assertTrue("No further connections expected", connectionIterator.hasNext());
+        if (!connectionIterator.hasNext()) {
+            throw new AssertionError("No further connections expected");
+        }
 
         MockSenderConnection currentConnection = connectionIterator.next();
         currentConnection.setUri(uri);
diff --git a/test/src/main/java/org/springframework/ws/mock/client/ThreadLocalMockWebServiceMessageSender.java b/test/src/main/java/org/springframework/ws/mock/client/ThreadLocalMockWebServiceMessageSender.java
index 6620be08..faa4e0fe 100644
--- a/test/src/main/java/org/springframework/ws/mock/client/ThreadLocalMockWebServiceMessageSender.java
+++ b/test/src/main/java/org/springframework/ws/mock/client/ThreadLocalMockWebServiceMessageSender.java
@@ -32,10 +32,18 @@ import org.springframework.ws.transport.WebServiceMessageSender;
 class ThreadLocalMockWebServiceMessageSender implements WebServiceMessageSender {
 
     public WebServiceConnection createConnection(URI uri) throws IOException {
-        return MockWebServiceMessageSenderHolder.get().createConnection(uri);
+        return getMock().createConnection(uri);
     }
 
     public boolean supports(URI uri) {
-        return MockWebServiceMessageSenderHolder.get().supports(uri);
+        return getMock().supports(uri);
+    }
+
+    private MockWebServiceMessageSender getMock() {
+        MockWebServiceMessageSender mock = MockWebServiceMessageSenderHolder.get();
+        if (mock == null) {
+            throw new AssertionError("No further connections expected");
+        }
+        return mock;
     }
 }
diff --git a/test/src/test/java/org/springframework/ws/mock/client/WebServiceMockTest.java b/test/src/test/java/org/springframework/ws/mock/client/WebServiceMockTest.java
index 38a96037..c1ee184a 100644
--- a/test/src/test/java/org/springframework/ws/mock/client/WebServiceMockTest.java
+++ b/test/src/test/java/org/springframework/ws/mock/client/WebServiceMockTest.java
@@ -153,6 +153,17 @@ public class WebServiceMockTest {
         template.sendSourceAndReceiveToResult(new StringSource(request), new StringResult());
         assertNull(MockWebServiceMessageSenderHolder.get());
     }
+    
+    @Test(expected = AssertionError.class)
+    public void unexpectedConnection() throws Exception {
+        String request = "<request xmlns='http://example.com'/>";
+        String response = "<response xmlns='http://example.com'/>";
+
+        expect(payload(request)).andRespond(withPayload(response));
+
+        template.sendSourceAndReceiveToResult(new StringSource(request), new StringResult());
+        template.sendSourceAndReceiveToResult(new StringSource(request), new StringResult());
+    }
 
 
 }