Couple of remarks without reading all details of all posts: Au3Stripper will create an outputfile that has the same encoding as the main sourcefile. Au3Check indeed doesn't support UTFxx with BOM, but AutoIt3Wrapper "works around that" because it will copy the original main script into a tempfile which is ascii encode and then runs the au3check against that. The reported errors are translated back for the original file/linenumber. EDIT: the new au3check in Beta does support UTF8 with BOM. Jos