diff --git a/test/src/main/java/org/springframework/ws/mock/client/PayloadMatcher.java b/test/src/main/java/org/springframework/ws/mock/client/PayloadDiffMatcher.java
similarity index 95%
rename from test/src/main/java/org/springframework/ws/mock/client/PayloadMatcher.java
rename to test/src/main/java/org/springframework/ws/mock/client/PayloadDiffMatcher.java
index ed9a0f28..fb716d0f 100644
--- a/test/src/main/java/org/springframework/ws/mock/client/PayloadMatcher.java
+++ b/test/src/main/java/org/springframework/ws/mock/client/PayloadDiffMatcher.java
@@ -35,11 +35,11 @@ import static junit.framework.Assert.fail;
  * @author Lukas Krecan
  * @since 2.0
  */
-class PayloadMatcher extends DiffMatcher {
+class PayloadDiffMatcher extends DiffMatcher {
 
     private final Source expected;
 
-    PayloadMatcher(Source expected) {
+    PayloadDiffMatcher(Source expected) {
         Assert.notNull(expected, "'expected' must not be null");
         this.expected = expected;
     }
diff --git a/test/src/main/java/org/springframework/ws/mock/client/WebServiceMock.java b/test/src/main/java/org/springframework/ws/mock/client/WebServiceMock.java
index 74cfd66d..5ca1b2ec 100644
--- a/test/src/main/java/org/springframework/ws/mock/client/WebServiceMock.java
+++ b/test/src/main/java/org/springframework/ws/mock/client/WebServiceMock.java
@@ -71,7 +71,7 @@ public abstract class WebServiceMock {
      */
     public static RequestMatcher payload(String payload) {
         Assert.notNull(payload, "'payload' must not be null");
-        return new PayloadMatcher(new StringSource(payload));
+        return new PayloadDiffMatcher(new StringSource(payload));
     }
 
     /**
@@ -82,7 +82,7 @@ public abstract class WebServiceMock {
      */
     public static RequestMatcher payload(Source payload) {
         Assert.notNull(payload, "'payload' must not be null");
-        return new PayloadMatcher(payload);
+        return new PayloadDiffMatcher(payload);
     }
 
     /**
@@ -93,7 +93,7 @@ public abstract class WebServiceMock {
      */
     public static RequestMatcher payload(Resource payload) {
         Assert.notNull(payload, "'payload' must not be null");
-        return new PayloadMatcher(createResourceSource(payload));
+        return new PayloadDiffMatcher(createResourceSource(payload));
     }
 
     /**
diff --git a/test/src/test/java/org/springframework/ws/mock/client/PayloadMatcherTest.java b/test/src/test/java/org/springframework/ws/mock/client/PayloadDiffMatcherTest.java
similarity index 88%
rename from test/src/test/java/org/springframework/ws/mock/client/PayloadMatcherTest.java
rename to test/src/test/java/org/springframework/ws/mock/client/PayloadDiffMatcherTest.java
index ada14ce2..e426e90f 100644
--- a/test/src/test/java/org/springframework/ws/mock/client/PayloadMatcherTest.java
+++ b/test/src/test/java/org/springframework/ws/mock/client/PayloadDiffMatcherTest.java
@@ -23,7 +23,7 @@ import org.junit.Test;
 
 import static org.easymock.EasyMock.*;
 
-public class PayloadMatcherTest {
+public class PayloadDiffMatcherTest {
 
     @Test
     public void match() throws Exception {
@@ -32,7 +32,7 @@ public class PayloadMatcherTest {
         expect(message.getPayloadSource()).andReturn(new StringSource(xml));
         replay(message);
 
-        PayloadMatcher matcher = new PayloadMatcher(new StringSource(xml));
+        PayloadDiffMatcher matcher = new PayloadDiffMatcher(new StringSource(xml));
         matcher.match(null, message);
 
         verify(message);
@@ -46,7 +46,7 @@ public class PayloadMatcherTest {
         replay(message);
 
         String expected = "<element2 xmlns='http://example.com'/>";
-        PayloadMatcher matcher = new PayloadMatcher(new StringSource(expected));
+        PayloadDiffMatcher matcher = new PayloadDiffMatcher(new StringSource(expected));
         matcher.match(null, message);
     }
 
diff --git a/xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactory.java b/xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactory.java
index d97d5631..897d782e 100644
--- a/xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactory.java
+++ b/xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactory.java
@@ -41,25 +41,11 @@ public abstract class XPathExpressionFactory {
 
     private static final Log logger = LogFactory.getLog(XPathExpressionFactory.class);
 
-    private static final String JAXEN_CLASS_NAME = "org.jaxen.XPath";
+    private static boolean jaxp13Available = JaxpVersion.isAtLeastJaxp13();
 
-    private static boolean jaxp13Available;
+    private static boolean jaxenAvailable =
+            ClassUtils.isPresent("org.jaxen.XPath", XPathExpressionFactory.class.getClassLoader());
 
-    private static boolean jaxenAvailable;
-
-    static {
-        // Check whether JAXP 1.3 is available
-        jaxp13Available = JaxpVersion.isAtLeastJaxp13();
-
-        // Check whether Jaxen is available
-        try {
-            ClassUtils.forName(JAXEN_CLASS_NAME);
-            jaxenAvailable = true;
-        }
-        catch (ClassNotFoundException ex) {
-            jaxenAvailable = false;
-        }
-    }
 
     /**
      * Create a compiled XPath expression using the given string.
@@ -87,6 +73,9 @@ public abstract class XPathExpressionFactory {
     public static XPathExpression createXPathExpression(String expression, Map<String, String> namespaces)
             throws IllegalStateException, XPathParseException {
         Assert.hasLength(expression, "expression is empty");
+        if (namespaces == null) {
+            namespaces = Collections.emptyMap();
+        }
         if (jaxp13Available) {
             try {
                 logger.trace("Creating [javax.xml.xpath.XPathExpression]");