diff --git a/actionpack/lib/abstract_controller/helpers.rb b/actionpack/lib/abstract_controller/helpers.rb
index 3913259ecc..8ff214f220 100644
--- a/actionpack/lib/abstract_controller/helpers.rb
+++ b/actionpack/lib/abstract_controller/helpers.rb
@@ -7,7 +7,7 @@ module AbstractController
     extend ActiveSupport::Concern
 
     included do
-      class_attribute :_helpers, default: Module.new
+      class_attribute :_helpers, default: define_helpers_module(self)
       class_attribute :_helper_methods, default: Array.new
     end
 
@@ -31,7 +31,7 @@ module AbstractController
       # independently of the child class's.
       def inherited(klass)
         helpers = _helpers
-        klass._helpers = Module.new { include helpers }
+        klass._helpers = define_helpers_module(klass, helpers)
         klass.class_eval { default_helper_module! } unless klass.anonymous?
         super
       end
@@ -170,6 +170,17 @@ module AbstractController
       end
 
       private
+        def define_helpers_module(klass, helpers = nil)
+          # In some tests inherited is called explicitly. In that case, just
+          # return the module from the first time it was defined
+          return klass.const_get(:HelperMethods) if klass.const_defined?(:HelperMethods, false)
+
+          mod = Module.new
+          klass.const_set(:HelperMethods, mod)
+          mod.include(helpers) if helpers
+          mod
+        end
+
         # Makes all the (instance) methods in the helper module available to templates
         # rendered through this controller.
         #
diff --git a/actionpack/test/controller/helper_test.rb b/actionpack/test/controller/helper_test.rb
index de8072a994..93a2ba1071 100644
--- a/actionpack/test/controller/helper_test.rb
+++ b/actionpack/test/controller/helper_test.rb
@@ -150,8 +150,8 @@ class HelperTest < ActiveSupport::TestCase
   end
 
   def test_default_helpers_only
-    assert_equal [JustMeHelper], JustMeController._helpers.ancestors.reject(&:anonymous?)
-    assert_equal [MeTooHelper, JustMeHelper], MeTooController._helpers.ancestors.reject(&:anonymous?)
+    assert_equal %w[JustMeHelper], JustMeController._helpers.ancestors.reject(&:anonymous?).map(&:to_s)
+    assert_equal %w[MeTooController::HelperMethods MeTooHelper JustMeHelper], MeTooController._helpers.ancestors.reject(&:anonymous?).map(&:to_s)
   end
 
   def test_base_helper_methods_after_clear_helpers