act_as_commentable The scope body needs to be callable

After update to rails 5.1 and added the acts_as_commentable (4.0.2) This is due to the new rails?

someone is having the same issue with this gem?

The log shows

ArgumentError in PostsController#show

The scope body needs to be callable.

class Comment < ActiveRecord::Base

  include ActsAsCommentable::Comment

  belongs_to :commentable, :polymorphic => true

in the posts controller

 def show
    @post = Post.find(params[:id])
    @comment = @post.comments.new
  end