use Win32::API;
$function = Win32::API::More->new(
    'mydll', 'int sum_integers(int a, int b)'
);

#### $^E is non-Cygwin only
die "Error: $^E" if ! $function;
#### or on Cygwin and non-Cygwin
die "Error: ".(Win32::FormatMessage(Win32::GetLastError())) if ! $function;