hi, FSPath>>#withExtension: is ignoring adding extension if extension is equal to end of basename. For example, if I want to produce: (FSFilesystem disk workingDirectory / 'Host') withExtension: 'st'. I should receive: /path/to/Host.st but I actually receive: /path/to/Host that can be fixed replacing FSPath>>#withExtension: extension | basename name | basename := self basename. ^ (basename endsWith: extension) ifTrue: [ self ] ifFalse: [name := basename copyUpToLast: self extensionDelimiter. self withName: name extension: extension] with: FSPath>>#withExtension: extension | basename name | basename := self basename. ^ (basename endsWith: '.', extension) ifTrue: [ self ] ifFalse: [name := basename copyUpToLast: self extensionDelimiter. self withName: name extension: extension] but I don't know if that would be a good solution :) best, Esteban