diff --git a/lib/searchkick/query.rb b/lib/searchkick/query.rb
index 1491b12..f943376 100644
--- a/lib/searchkick/query.rb
+++ b/lib/searchkick/query.rb
@@ -864,10 +864,11 @@ module Searchkick
       }
     end
 
-    # TODO id transformation for arrays
     def set_order(payload)
       order = options[:order].is_a?(Enumerable) ? options[:order] : {options[:order] => :asc}
       id_field = :_id
+      # TODO no longer map id to _id in Searchkick 5
+      # since sorting on _id is deprecated in Elasticsearch
       payload[:sort] = order.is_a?(Array) ? order : Hash[order.map { |k, v| [k.to_s == "id" ? id_field : k, v] }]
     end
 
diff --git a/test/order_test.rb b/test/order_test.rb
index 4bfdacc..d49ecc8 100644
--- a/test/order_test.rb
+++ b/test/order_test.rb
@@ -11,13 +11,18 @@ class OrderTest < Minitest::Test
     assert_order "product", ["Product A", "Product B", "Product C", "Product D"], order: "name"
   end
 
+  # TODO no longer map id to _id in Searchkick 5
+  # since sorting on _id is deprecated in Elasticsearch
   def test_id
     skip if cequel?
 
     store_names ["Product A", "Product B"]
     product_a = Product.where(name: "Product A").first
     product_b = Product.where(name: "Product B").first
-    assert_order "product", [product_a, product_b].sort_by { |r| r.id.to_s }.map(&:name), order: {id: :asc}
+    _, stderr = capture_io do
+      assert_order "product", [product_a, product_b].sort_by { |r| r.id.to_s }.map(&:name), order: {id: :asc}
+    end
+    assert_match "Loading the fielddata on the _id field is deprecated", stderr
   end
 
   def test_multiple
@@ -30,6 +35,7 @@ class OrderTest < Minitest::Test
   end
 
   def test_unmapped_type
+    Product.search_index.refresh
     assert_order "product", [], order: {not_mapped: {unmapped_type: "long"}}
   end
 
--
libgit2 0.21.0