Also change the spec at https://github.com/rapid7/metasploit_data_models/blob/master/spec/app/models/mdm/host_spec.rb#L389 from 

```ruby
it { should ensure_inclusion_of(:arch).in_array(architectures).allow_nil }
```

to 

```ruby
it { should ensure_inclusion_of(:arch).in_array(architectures).allow_blank }
```