diff --git a/src/test/resources/org/apache/commons/digester3/xmlrules/atom-content.xml b/src/test/resources/org/apache/commons/digester3/xmlrules/atom-content.xml
index 226b28c..b008fb6 100644
--- a/src/test/resources/org/apache/commons/digester3/xmlrules/atom-content.xml
+++ b/src/test/resources/org/apache/commons/digester3/xmlrules/atom-content.xml
@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE digester-rules PUBLIC "-//Apache Commons //DTD digester-rules XML V1.0//EN" "http://commons.apache.org/digester/dtds/digester-rules-3.0.dtd">
 <!--
    Licensed to the Apache Software Foundation (ASF) under one or more
    contributor license agreements.  See the NOTICE file distributed with