laravel 5.1 error in validating doc docx type file

Hi i am facing a docx type validation problem. I tried

$validator = Validator::make($request->all(), [
            'resume'   => 'mimes:doc,pdf,docx'
        ]);

It will upload pdf file with no error but whenever i try to upload docx files it gives validation error 'must be a file of type: doc, pdf, docx'
any idea

via Chebli Mohamed