diff --git a/src/main/java/org/dita/index/IndexPreprocessor.java b/src/main/java/org/dita/index/IndexPreprocessor.java
index 36f4bb8..ecdaad4 100644
--- a/src/main/java/org/dita/index/IndexPreprocessor.java
+++ b/src/main/java/org/dita/index/IndexPreprocessor.java
@@ -35,7 +35,6 @@ RELIANCE, OR CONSEQUENTIAL DAMAGES (INCLUDING BUT NOT LIMITED TO LOSS OF
 import static org.dita.dost.util.Constants.*;
 
 import java.util.*;
-import javax.xml.parsers.DocumentBuilder;
 import org.dita.dost.log.DITAOTLogger;
 import org.dita.dost.util.XMLUtils;
 import org.dita.index.configuration.IndexConfiguration;
@@ -101,8 +100,7 @@ public void setLogger(final DITAOTLogger logger) {
    * @return read index terms
    */
   IndexPreprocessResult process(final Document input) {
-    final DocumentBuilder documentBuilder = XMLUtils.getDocumentBuilder();
-    final Document doc = documentBuilder.newDocument();
+    final Document doc = input.getImplementation().createDocument(null, null, null);
     final Node rootElement = input.getDocumentElement();
     final List<IndexEntry> indexes = new ArrayList<>();
     final Node node = processCurrNode(rootElement, doc, indexes::add).get(0);
diff --git a/src/main/java/org/dita/index/IndexPreprocessorTask.java b/src/main/java/org/dita/index/IndexPreprocessorTask.java
index d834dd7..90f6e4f 100644
--- a/src/main/java/org/dita/index/IndexPreprocessorTask.java
+++ b/src/main/java/org/dita/index/IndexPreprocessorTask.java
@@ -38,6 +38,8 @@ RELIANCE, OR CONSEQUENTIAL DAMAGES (INCLUDING BUT NOT LIMITED TO LOSS OF
 import java.util.Collection;
 import java.util.Locale;
 import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.transform.OutputKeys;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerFactory;
@@ -47,7 +49,6 @@ RELIANCE, OR CONSEQUENTIAL DAMAGES (INCLUDING BUT NOT LIMITED TO LOSS OF
 import org.apache.tools.ant.Project;
 import org.apache.tools.ant.Task;
 import org.dita.dost.log.DITAOTAntLogger;
-import org.dita.dost.util.XMLUtils;
 import org.dita.index.configuration.IndexConfiguration;
 import org.dita.index.configuration.ParseException;
 import org.w3c.dom.Document;
@@ -71,12 +72,13 @@ public class IndexPreprocessorTask extends Task {
   public void execute() throws BuildException {
     checkParameters();
 
-    final DocumentBuilder documentBuilder = XMLUtils.getDocumentBuilder();
-
     final Document doc;
     try {
+      final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+      factory.setNamespaceAware(true);
+      final DocumentBuilder documentBuilder = factory.newDocumentBuilder();
       doc = documentBuilder.parse(input);
-    } catch (SAXException | IOException e) {
+    } catch (SAXException | IOException | ParserConfigurationException e) {
       throw new BuildException(e);
     }