utf8 warning when installing DBI 1.604

Lo,

I get the following warning when installing DBI. All tests pass so I don't think there's a problem, but could someone elaborate on the warning please?

*** Your LANG environment variable is set to 'en_US.UTF-8'
*** This is known to cause problems for some perl installations.
*** If you get test failures, please try again with LANG unset.
*** Please also email dbi-dev@xxxxxxxx and include the output of 'perl -V'

Thanks

John
.