diff --git a/java/external/src/javax/xml/xpath/XPathException.java b/java/external/src/javax/xml/xpath/XPathException.java
index 17d94a7..a0b5463 100644
--- a/java/external/src/javax/xml/xpath/XPathException.java
+++ b/java/external/src/javax/xml/xpath/XPathException.java
@@ -63,7 +63,7 @@ public class XPathException extends Exception {
      * @throws NullPointerException if <code>cause</code> is <code>null</code>.
      */
     public XPathException(Throwable cause) {
-        super();
+        super(cause == null ? null : cause.toString());
         this.cause = cause;
         if ( cause == null ) {
             throw new NullPointerException ( "cause can't be null");