m lib/will_paginate/finders/active_record.rb Based on https://github.com/JackDanger/will_paginate/commit/e97acba1b94f2a6d19d5a271ddfa5ebc80d3d822 AssociationCollection was functionally renamed to CollectionAssociation No need to detect on this branch - AssociationCollection is not coming back! Rails 3.1 and eariler Rails 3.x branches now supported.