diff --git a/src/main/java/org/dom4j/swing/LeafTreeNode.java b/src/main/java/org/dom4j/swing/LeafTreeNode.java

index 94706c6..69b5465 100644

--- a/src/main/java/org/dom4j/swing/LeafTreeNode.java

+++ b/src/main/java/org/dom4j/swing/LeafTreeNode.java

@@ -24,7 +24,7 @@ import org.dom4j.Node;

  * @version $Revision: 1.7 $

  */

 public class LeafTreeNode implements TreeNode {

-    protected static final Enumeration<?> EMPTY_ENUMERATION = new Enumeration() {

+    protected static final Enumeration<? extends TreeNode> EMPTY_ENUMERATION = new Enumeration() {

         public boolean hasMoreElements() {

             return false;

         }

@@ -54,7 +54,7 @@ public class LeafTreeNode implements TreeNode {

     // TreeNode methods

     // -------------------------------------------------------------------------

-    public Enumeration<?> children() {

+    public Enumeration<? extends TreeNode> children() {

         return EMPTY_ENUMERATION;

     }