Format is "reserved"

I am using grape, grape entity, and rails together for an api. I have a rails model that has a column, format. When I try to expose this column, I get an error that looks something like -

too few arguments
... /gems/grape-entity-0.5.1/lib/grape_entity/entity.rb:482:in `format'
... /gems/grape-entity-0.5.1/lib/grape_entity/entity.rb:482:in `delegate_attribute'

The entity in question

class Content < Grape::Entity
  expose :id, :guid, :slug, :metadata, :url, :format
end

I am using grape@0.16.2 and grape-entity@0.5.1

Reproduce the failure with the Content entity and its exposed format column using grape 0.16.2 and grape-entity 0.5.1. Start at grape_entity/entity.rb:482, where format is reported in delegate_attribute; done means exposing format no longer raises the argument error and the column is returned correctly.