unicode characters in .m files

I would like to use unicode characters in the comments of .m files, e.g., the ≈ (approximately equal, Unicode U+2248), for which there is no acceptable short substitute, as in <= for ≤. Note that ~ (tilde) represents logical negation, almost the opposite sense of ≈, and is therefore NOT an acceptable substitute. I can type the unicode character into the .m file and save it, but when I re-open the .m file, it appears as a question mark. The command [feature('DefaultCharacterSet', 'UTF8')] doesn't help. Unicode has been around for 20 years; why doesn't Matlab support unicode properly yet?