file_column plugin and mime types

I am running into an error using file_column plugin, and am not sure
where the problem lies. I am trying to upload Microsoft Excel files and
Adobe Illustrator files, but they are incorrectly identified as
Microsoft Word and Adobe Acrobat files, respectively.

I am not sure if this is a problem with the file_column plugin or
rmagick. Any ideas?

Looking into the matter futher, it actually seems that the problem lies
with the UNIX 'file' executable that the file_column uses to 'guess'
the mime type. What is the best way to disabling this check? Should I
alter the code directly?