Index: src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ContentTypeManager.java
===================================================================
--- src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ContentTypeManager.java	(revision 1636144)
+++ src/ooxml/java/org/apache/poi/openxml4j/opc/internal/ContentTypeManager.java	(working copy)
@@ -444,7 +444,7 @@
 	 */
 	private void appendSpecificTypes(Element root,
 			Entry<PackagePartName, String> entry) {
-        Element specificType = root.getOwnerDocument().createElement(OVERRIDE_TAG_NAME);
+        Element specificType = root.getOwnerDocument().createElementNS(TYPES_NAMESPACE_URI, OVERRIDE_TAG_NAME);
         specificType.setAttribute(PART_NAME_ATTRIBUTE_NAME, entry.getKey().getName());
         specificType.setAttribute(CONTENT_TYPE_ATTRIBUTE_NAME, entry.getValue());
         root.appendChild(specificType);
@@ -460,7 +460,7 @@
 	 * @see #save(java.io.OutputStream)
 	 */
 	private void appendDefaultType(Element root, Entry<String, String> entry) {
-        Element defaultType = root.getOwnerDocument().createElement(DEFAULT_TAG_NAME);
+        Element defaultType = root.getOwnerDocument().createElementNS(TYPES_NAMESPACE_URI, DEFAULT_TAG_NAME);
         defaultType.setAttribute(EXTENSION_ATTRIBUTE_NAME, entry.getKey());
         defaultType.setAttribute(CONTENT_TYPE_ATTRIBUTE_NAME, entry.getValue());
         root.appendChild(defaultType);
Index: src/ooxml/java/org/apache/poi/openxml4j/opc/internal/marshallers/ZipPartMarshaller.java
===================================================================
--- src/ooxml/java/org/apache/poi/openxml4j/opc/internal/marshallers/ZipPartMarshaller.java	(revision 1636144)
+++ src/ooxml/java/org/apache/poi/openxml4j/opc/internal/marshallers/ZipPartMarshaller.java	(working copy)
@@ -36,8 +36,8 @@
 import org.apache.poi.openxml4j.opc.internal.PartMarshaller;
 import org.apache.poi.openxml4j.opc.internal.ZipHelper;
 import org.apache.poi.util.DocumentHelper;
+import org.apache.poi.util.POILogFactory;
 import org.apache.poi.util.POILogger;
-import org.apache.poi.util.POILogFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 
@@ -134,7 +134,7 @@
 
 		for (PackageRelationship rel : rels) {
 			// the relationship element
-            Element relElem = xmlOutDoc.createElement(PackageRelationship.RELATIONSHIP_TAG_NAME);
+            Element relElem = xmlOutDoc.createElementNS(PackageNamespaces.RELATIONSHIPS, PackageRelationship.RELATIONSHIP_TAG_NAME);
             root.appendChild(relElem);
 
 			// the relationship ID