3 files changed, 2 insertions, 9 deletions
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index a70ba0d2e3..1a2cbaab65 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -60,17 +60,11 @@ module ActionController
     include ActionController::Compatibility
 
     def self.inherited(klass)
-      ::ActionController::Base.subclasses << klass.to_s
       super
       klass.helper :all
     end
 
-    def self.subclasses
-      @subclasses ||= []
-    end
-
     config_accessor :asset_host, :asset_path
-
     ActiveSupport.run_load_hooks(:action_controller, self)
   end
 end
diff --git a/actionpack/lib/action_controller/railtie.rb b/actionpack/lib/action_controller/railtie.rb
index 86395c4d93..9261422f0b 100644
--- a/actionpack/lib/action_controller/railtie.rb
+++ b/actionpack/lib/action_controller/railtie.rb
@@ -2,7 +2,6 @@ require "rails"
 require "action_controller"
 require "action_dispatch/railtie"
 require "action_view/railtie"
-require "active_support/core_ext/class/subclasses"
 require "active_support/deprecation/proxy_wrappers"
 require "active_support/deprecation"
 
diff --git a/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb b/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb
index e122bdf232..05e8dfded6 100644
--- a/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/deprecated_mapper.rb
@@ -19,8 +19,8 @@ module ActionDispatch
 
       def in_memory_controller_namespaces
         namespaces = Set.new
-        ActionController::Base.subclasses.each do |klass|
-          controller_name = klass.underscore
+        ActionController::Base.descendants.each do |klass|
+          controller_name = klass.name.underscore
           namespaces << controller_name.split('/')[0...-1].join('/')
         end
         namespaces.delete('')