diff --git a/CHANGELOG.md b/CHANGELOG.md
index e7eb044b..2282ddbd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@ Features:
     associations for JSON and Attributes adapters via the `include` option (@NullVoxPopuli, @beauby).
 
 Fixes:
+- [#1214](https://github.com/rails-api/active_model_serializers/pull/1214) retrieve the key from the reflection options when building associations (@NullVoxPopuli, @hut8)
 
 Misc:
 - [#1178](https://github.com/rails-api/active_model_serializers/pull/1178) env CAPTURE_STDERR=false lets devs see hard failures (@bf4)
diff --git a/lib/active_model/serializer/associations.rb b/lib/active_model/serializer/associations.rb
index 86c5752c..af627a13 100644
--- a/lib/active_model/serializer/associations.rb
+++ b/lib/active_model/serializer/associations.rb
@@ -92,7 +92,8 @@ module ActiveModel
 
         Enumerator.new do |y|
           self.class._reflections.each do |reflection|
-            next unless include_tree.key?(reflection.name)
+            key = reflection.options.fetch(:key, reflection.name)
+            next unless include_tree.key?(key)
             y.yield reflection.build_association(self, instance_options)
           end
         end
diff --git a/test/action_controller/json_api/linked_test.rb b/test/action_controller/json_api/linked_test.rb
index 04ea4c99..8d541f5b 100644
--- a/test/action_controller/json_api/linked_test.rb
+++ b/test/action_controller/json_api/linked_test.rb
@@ -46,6 +46,11 @@ module ActionController
             render json: @post, include: [:author], adapter: :json_api
           end
 
+          def render_resource_with_include_of_custom_key_by_original
+            setup_post
+            render json: @post, include: [:reviews], adapter: :json_api, serializer: PostWithCustomKeysSerializer
+          end
+
           def render_resource_with_nested_include
             setup_post
             render json: @post, include: [comments: [:author]], adapter: :json_api
@@ -137,6 +142,18 @@ module ActionController
           assert_equal expected_linked, response['included']
         end
 
+        def test_render_resource_with_include_of_custom_key_by_original
+          get :render_resource_with_include_of_custom_key_by_original
+          response = JSON.parse(@response.body)
+          assert response.key? 'included'
+
+          relationships = response['data']['relationships']
+
+          assert_includes relationships, 'reviews'
+          assert_includes relationships, 'writer'
+          assert_includes relationships, 'site'
+        end
+
         def test_render_resource_with_nested_include
           get :render_resource_with_nested_include
           response = JSON.parse(@response.body)