I've found it: Loading Pastell into latest image 60342 using: Metacello new smalltalkhubUser: 'Pharo' project: 'MetaRepoForPharo50'; configuration: 'Pastell'; version: #stable; load. the tests are green now. And it is also not a difference between Mac and Windows When the method looks like testDNU | xml document html testElements | xml := '<html><testElement/><testElement/></html>'. document := XMLDOMParser parse: xml readStream. html := document html. testElements := html testElement. self assert: testElements size = 2. self assert: testElements first name = #testElement. self assert: testElements last name = #testElement it works When I exchange the tag "testElement" agains "head" it does not work as I reported in my last mail: testDNU | xml document html testElements | xml := '<html><head/><head/></html>'. document := XMLDOMParser parse: xml readStream. html := document html. testElements := html head. self assert: testElements size = 2. self assert: testElements first name = #head. self assert: testElements last name = #head Now the assertions fail although only the tag name/message changed. Reason is simple: there is a #head method in Object from Morphic just returning self. For whatever reason but this makes the difference. Lesson learned: take care with DNU tricks ;) Sorry for the noise! Bye T.