diff --git a/test/fixtures/active_record.rb b/test/fixtures/active_record.rb
index 6126cca0..0922c7dd 100644
--- a/test/fixtures/active_record.rb
+++ b/test/fixtures/active_record.rb
@@ -429,6 +429,18 @@
     t.integer :version
     t.timestamps null: false
   end
+
+  # Tables for testing Issue #1473: Polymorphic has_many with foreign_key_on: :related
+  create_table :articles, force: true do |t|
+    t.string :title
+    t.timestamps null: false
+  end
+
+  create_table :article_comments, force: true do |t|
+    t.text :content
+    t.references :commentable, polymorphic: true, index: true
+    t.timestamps null: false
+  end
 end
 
 ### MODELS
@@ -868,6 +880,15 @@ class ListItem < ActiveRecord::Base
   belongs_to :list, inverse_of: :items
 end
 
+# Models for testing Issue #1473: Polymorphic has_many with foreign_key_on: :related
+class Article < ActiveRecord::Base
+  has_many :article_comments, as: :commentable
+end
+
+class ArticleComment < ActiveRecord::Base
+  belongs_to :commentable, polymorphic: true
+end
+
 ### CONTROLLERS
 class SessionsController < ActionController::Base
   include JSONAPI::ActsAsResourceController
@@ -1230,6 +1251,13 @@ class IndicatorsController < JSONAPI::ResourceController
 class RobotsController < JSONAPI::ResourceController
 end
 
+# Controllers for testing Issue #1473
+class ArticlesController < JSONAPI::ResourceController
+end
+
+class ArticleCommentsController < JSONAPI::ResourceController
+end
+
 ### RESOURCES
 class BaseResource < JSONAPI::Resource
   abstract
@@ -2691,6 +2719,17 @@ class RobotResource < ::JSONAPI::Resource
   end
 end
 
+# Resources for testing Issue #1473: Polymorphic has_many with foreign_key_on: :related
+class ArticleResource < JSONAPI::Resource
+  attribute :title
+  has_many :article_comments, foreign_key_on: :related
+end
+
+class ArticleCommentResource < JSONAPI::Resource
+  attribute :content
+  has_one :commentable, polymorphic: true
+end
+
 # Models and Resources for testing Issue #1467: ActiveModel-based resources
 # ActiveModel class without ActiveRecord
 class SimpleModel
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 964ef224..191e181b 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -340,6 +340,10 @@ class CatResource < JSONAPI::Resource
   jsonapi_resources :employees
   jsonapi_resources :robots
 
+  # Routes for testing Issue #1473
+  jsonapi_resources :articles
+  jsonapi_resources :article_comments
+
   jsonapi_resources :lists
   jsonapi_resources :list_items