file type crt as mime

I do face an issue when using upload library

since when trying to upload a CRT file (Certificate File) which has a mime type of Content-Type: application/pkix-cert 


it gives me file type not allowed

I checked the mimes.php and it has a record for crt as follow:

'crt'   => array('application/x-x509-ca-cert', 'application/x-x509-user-cert', 'application/pkix-cert')

so any suggestions please

note: when I use $config['allowed_types']        = '*'; 
it works without errors