There's also an XS module available which might be a useful alternative: File::LibMagic

Example (shameless theft from the docs):

 use File::LibMagic ':easy';

         print MagicBuffer("Hello World\n"),"\n";
         # returns "ASCII text"

         print MagicFile("/bin/ls"),"\n";
         # returns "ELF 32-bit LSB executable, Intel 80386, version 1 
+(SYSV)"
         # on my system
[download]