Unable to convert U+2605 from UTF-8 to US-ASCII

Hello

When I do:

gem install compass compass-normalize compass-recipes modular-scale

On debian wheezy docker vm I get this back:

unable to convert U+2605 from UTF-8 to US-ASCII for lib/compass/commands/watch_project.rb, skipping
Installing ri documentation for compass-normalize-1.5…
Installing ri documentation for compass-recipes-0.3.0…
Installing ri documentation for modular-scale-2.0.6…
unable to convert “\xC2” to UTF-8 in conversion from ASCII-8BIT to UTF-8 to US-ASCII for license.md, skipping
unable to convert “\xE2” to UTF-8 in conversion from ASCII-8BIT to UTF-8 to US-ASCII for readme.md, skipping
Installing RDoc documentation for compass-1.0.3…
unable to convert U+2605 from UTF-8 to US-ASCII for lib/compass/commands/watch_project.rb, skipping
Installing RDoc documentation for compass-normalize-1.5…
Installing RDoc documentation for compass-recipes-0.3.0…
Installing RDoc documentation for modular-scale-2.0.6…
unable to convert “\xC2” to UTF-8 in conversion from ASCII-8BIT to UTF-8 to US-ASCII for license.md, skipping
unable to convert “\xE2” to UTF-8 in conversion from ASCII-8BIT to UTF-8 to US-ASCII for readme.md, skipping

I have the locales installed if this would be referring to it.
Any ideas?

Thanks