Use boolean attribute helper methods when extending from Virtus.model on the fly

Let's say I have a Virtus model User with a boolean attribute active:

class User
  include Virtus.model 
  attribute :active, Boolean, default: false, lazy: true
end

Then I could user a helper method active?:

User.new.active? # => false
User.new(active: true).active? # => true

But when I try to extend from Virtus.model and define a boolean attribute on the fly:

class User; end
user = User.new
user.extend(Virtus.model)
user.attribute(:active, Axiom::Types::Boolean, default: false, lazy: true)
user.active = true

and use a helper method active? I get a NoMethodError kinda exception.

user.active? # => NoMethodError: undefined method `active?' for

Is there any possibility of using helper methods in this situation?