Hi, This is OK: {ok, H} = file:open("foo.gz", [read, compressed]). {ok, _} = file:pread(H, 0, 4096). And this is not: {ok, H} = file:open("foo.gz", [read, raw, compressed]). file:pread(H, 0, 4096). {error,ebadf} Why? The doc doesn't warn about this limitation. Regards, Zabrane