make sure to provide alternative formats for macOS 10.15 and earlier. This issue is especially tricky to detect if you provide both, 16x16 and 16x16@2x icons, because if you connect your Mac to a non-retina monitor, the non-retina 16x16 icon will be used and thus the icon will be displayed scrambled. The field does not seem to be used in application icons and can safely be ignored. Additionally, if you don't provide the smaller icon sizes at all the bug will also manifest when the OS scales down your larger PNG/JPEG 2000 icons, so make sure to render smaller sizes and include them. Support Various image viewers can load *.icns files, and free and open source converters from or to PNG also exist. GTK+ can load *.icns resources since 2007. Other tools supporting the format include the Apple Icon Composer and icns Browser, The Iconfactory, and IconBuilder. MacOS offers the built-in iconutil command line tool to pack and unpack *.icns files. See also ICO format on Windows X PixMap format for X11 References External links IconFamily (last update 2013) – Open source Objective C class to read and write Apple icns files osxiconutils (not maintained) – Command line tools to work with Apple icns files icnsutil – Python library to read and write icns files icns - Rust crate to read and write icns files Graphics file formats MacOS Computer icons