Hi: using lxml 3.3.5, we have XML documents with elements having QName type values. We would like to implement etree.cleanup_namespaces but are finding that this affects downstream parsers/validators complaining about undeclared namespace prefixes. Below is an isolated example: from lxml import etree nsmap = { 'ogc': 'http://www.opengis.net/ogc', 'ows': 'http://www.opengis.net/ows', 'gml': 'http://www.opengis.net/gml' } root = etree.Element('{http://www.opengis.net/ogc}Filter', nsmap=nsmap) typename = etree.SubElement(root, '{http://www.opengis.net/ogc}typeName') typename.text = etree.QName('http://www.opengis.net/gml', 'Envelope') typename2 = etree.SubElement(root, '{http://www.opengis.net/ogc}typeName') typename2.text = etree.QName('{http://www.opengis.net/gml}Envelope') print etree.tostring(root, pretty_print=True) etree.cleanup_namespaces(root) print etree.tostring(root, pretty_print=True) Here we would like the gml namespace declaration, but it looks like cleanup_namespaces is throwing out namespace declarations even if they apply to element content. Are there any workarounds we can use/implement to cleanup unused namespaces while preserving those for element content per above? Thanks in advance. ..Tom