Error updating the Refinery CMS Gem

I am trying to update the Refinery CMS gem I have installed on my mac. I am using RVM but don't understand it very well. Here's what happens:

Get-2:~ richardjburton$ gem install refinerycms
Building native extensions.  This could take a while...
ERROR:  Error installing refinerycms:
    ERROR: Failed to build gem native extension.

        /Users/richardjburton/.rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb
creating Makefile

make
sh: make: command not found

Any ideas?

Solution

This looks like you don't have the OS X developer tools installed. You should try installing XCode. Did you recently upgrade from Snow Leopard to Lion or anything like that? I had a similar issue when I upgraded from Snow Leopard to Lion, I had to download the new version of XCode. If you have the installation discs, it's on the 2nd disc. If not, it's available in the Mac AppStore for free, but its about 4GB, so make sure you have the time to download it.