具有现有模型名称的外键

我有以下迁移:

class CreateTables < ActiveRecord::Migration[5.2]
  def change
    create_table "customers" do |t|
      t.string "name"
    end

    create_table "items" do |t|
      t.integer "customer"
    end
  end
end

和模型:

class Customer < ApplicationRecord
  has_many :items, foreign_key: :customer
end

class Item < ApplicationRecord
  belongs_to :customer, foreign_key: :customer
end

以下代码无限循环,因为 foreign key 与现有模型同名:

2.5.1 :001 > Customer.create(name: "John")
=> #<Customer id: 1, name: "John">

2.5.1 :002 > Customer.first
=> #<Customer id: 1, name: "John"> 

2.5.1 :003 > Customer.first.items
Traceback (most recent call last):
SystemStackError (stack level too deep)

如何引用与现有名称冲突的列?