``` irb(main):016:0> Virtus::Attribute.build(true).is_a?(Virtus::Attribute::Boolean) => true irb(main):017:0> Virtus::Attribute.build(false).is_a?(Virtus::Attribute::Boolean) => false ``` Found it out while investigating a [bug](https://github.com/ruby-grape/grape/issues/1577) in grape.