diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 59f7a03..05ed7a4 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -65,6 +65,21 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal person, person.readers.first.person
   end
 
+  def test_find_or_create_by_with_additional_parameters
+    post = Post.create! :title => 'test_find_or_create_by_with_additional_parameters', :body => 'this is the body'
+    comment = post.comments.create! :body => 'test comment body', :type => 'test'
+
+    assert_equal comment, post.comments.find_or_create_by_body('test comment body')
+
+    # 2.3.8: success
+    # 2.3.9:
+    # ArgumentError: Unknown key(s): type, body
+    #     ./test/cases/../../../activesupport/lib/active_support/core_ext/hash/keys.rb:47:in `assert_valid_keys'
+    post.comments.find_or_create_by_body(:body => 'other test comment body', :type => 'test')
+    assert_equal 2, post.comments.count
+    assert_equal 2, post.comments.length
+  end
+
   def test_find_or_create
     person = Person.create! :first_name => 'tenderlove'
     post   = Post.find :first