Oh wait, I see what you're saying..

In this instance then I'd be more tempted to say:

``` ruby
problematic_cpu? = Hardware::CPU.family == :haswell && Hardware::CPU.extmodel >= 4

if build.without?('ssse3') || MacOS.version <= :snow_leopard || problematic_cpu?
  args << '-no-ssse3' 
end
```

I figure that this Haswell will more than likely have issues compiling SSSE3 extensions on Lion and Mountain Lion too, and the number of 2013 machines running those operating systems will be negligible anyway.  Thoughts?