rvm无法安装ruby-1.9.3-p484

我正在尝试更新我的OctoPress博客并收到错误消息

未安装ruby-1.9.3-p484.

当我输入命令

rvm install ruby​​-1.9.3-p484我得到了错误:

Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.8/x86_64/ruby-1.9.3-p484.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for osx.
Error: No available formula for gcc46 
Installing requirements for osx.
Updating system.........
Error running 'requirements_osx_brew_update_system ruby-1.9.3-p484',
please read /Users/stevenbrooks1111/.rvm/log/1386191431_ruby-1.9.3-p484/update_system.log
Requirements installation failed with status: 1.

不知道这里发生了什么.我现在有

ruby-1.9.3-p429 [ x86_64 ]
ruby-2.0.0-p195 [ x86_64 ]
ruby-2.0.0-p353 [ x86_64 ]

安装在我的电脑上.