diff -r db5418b04c63 -r 4b938619848b src/XMLDocumentConstructor.h
--- a/src/XMLDocumentConstructor.h	Sun Feb 21 22:11:49 2021 +0100
+++ b/src/XMLDocumentConstructor.h	Sun Feb 21 23:52:46 2021 +0100
@@ -58,8 +58,9 @@
 				} else {
 					element = parent->add_child(elementName);
 				}
-
+				
 				for (size_t i = 0; i < htmlNode->v.element.attributes.length; i++) {
+					// FIXME: if the xmlns was set in exportTo() according to the DOCTYPE, we should not add xmlns attribute here (otherwise we would have two xmlns attributes and thus invalid xml)
 					GumboAttribute* htmlAttribute = static_cast<GumboAttribute*> (htmlNode->v.element.attributes.data[i]);
 					element->set_attribute(htmlAttribute->name, htmlAttribute->value);
 				}