--- 
+++ 
@@ -26,7 +26,7 @@
     public void describeTo(Description description) {
         description.appendText("same(");
         appendQuoting(description);
-        description.appendText(wanted.toString());
+        description.appendText(wanted == null? "null" : wanted.toString());
         appendQuoting(description);
         description.appendText(")");
     }