diff --git a/lib/active_model_serializers/railtie.rb b/lib/active_model_serializers/railtie.rb
index 1d95ceac..1c8ff3c9 100644
--- a/lib/active_model_serializers/railtie.rb
+++ b/lib/active_model_serializers/railtie.rb
@@ -25,8 +25,11 @@ module ActiveModelSerializers
     # and also before eager_loading (if enabled).
     initializer 'active_model_serializers.set_configs', :after => 'action_controller.set_configs' do
       ActiveModelSerializers.logger = Rails.configuration.action_controller.logger
-      ActiveModelSerializers.config.cache_store     = Rails.configuration.action_controller.cache_store
       ActiveModelSerializers.config.perform_caching = Rails.configuration.action_controller.perform_caching
+      # We want this hook to run after the config has been set, even if ActionController has already loaded.
+      ActiveSupport.on_load(:action_controller) do
+        ActiveModelSerializers.config.cache_store = cache_store
+      end
     end
 
     generators do |app|
diff --git a/test/serializers/caching_configuration_test_isolated.rb b/test/serializers/caching_configuration_test_isolated.rb
index 1b6d5541..82e497b2 100644
--- a/test/serializers/caching_configuration_test_isolated.rb
+++ b/test/serializers/caching_configuration_test_isolated.rb
@@ -37,6 +37,7 @@ class CachingConfigurationTest < ActiveSupport::TestCase
         app.config.action_controller.perform_caching = true
         app.config.action_controller.cache_store = ActiveSupport::Cache.lookup_store(:memory_store)
       end
+      controller_cache_store # Force ActiveSupport.on_load(:action_controller) to run
     end
 
     test 'it sets perform_caching to true on AMS.config and serializers' do
@@ -103,6 +104,7 @@ class CachingConfigurationTest < ActiveSupport::TestCase
         app.config.action_controller.perform_caching = false
         app.config.action_controller.cache_store = ActiveSupport::Cache.lookup_store(:memory_store)
       end
+      controller_cache_store # Force ActiveSupport.on_load(:action_controller) to run
     end
 
     test 'it sets perform_caching to false on AMS.config and serializers' do
diff --git a/test/support/rails_app.rb b/test/support/rails_app.rb
index bc2fc8d1..9d44a59a 100644
--- a/test/support/rails_app.rb
+++ b/test/support/rails_app.rb
@@ -5,7 +5,6 @@ module ActiveModelSerializers
       config.secret_key_base = 'abc123'
       config.active_support.test_order = :random
       config.action_controller.perform_caching = true
-      ActionController::Base.cache_store = :memory_store
     end
 
     app.routes.default_url_options = { host: 'example.com' }