diff --git a/lib/shoulda/matchers/integrations/libraries/action_controller.rb b/lib/shoulda/matchers/integrations/libraries/action_controller.rb
index 013832e0e..ff62c4100 100644
--- a/lib/shoulda/matchers/integrations/libraries/action_controller.rb
+++ b/lib/shoulda/matchers/integrations/libraries/action_controller.rb
@@ -12,15 +12,17 @@ class ActionController
           def integrate_with(test_framework)
             test_framework.include(matchers_module, type: :controller)
 
-            include_into(::ActionController::TestCase, matchers_module) do
-              def subject # rubocop:disable Lint/NestedMethodDefinition
-                @controller
+            self.tap do |instance|
+              ActiveSupport.on_load(:action_controller_test_case, run_once: true) do
+                instance.include_into(::ActionController::TestCase, instance.matchers_module) do
+                  def subject # rubocop:disable Lint/NestedMethodDefinition
+                    @controller
+                  end
+                end
               end
             end
           end
 
-          private
-
           def matchers_module
             Shoulda::Matchers::ActionController
           end
diff --git a/lib/shoulda/matchers/integrations/libraries/routing.rb b/lib/shoulda/matchers/integrations/libraries/routing.rb
index 3399c22bd..0e0501346 100644
--- a/lib/shoulda/matchers/integrations/libraries/routing.rb
+++ b/lib/shoulda/matchers/integrations/libraries/routing.rb
@@ -12,11 +12,13 @@ class Routing
           def integrate_with(test_framework)
             test_framework.include(matchers_module, type: :routing)
 
-            include_into(::ActionController::TestCase, matchers_module)
+            self.tap do |instance|
+              ActiveSupport.on_load(:action_controller_test_case, run_once: true) do
+                instance.include_into(::ActionController::TestCase, instance.matchers_module)
+              end
+            end
           end
 
-          private
-
           def matchers_module
             Shoulda::Matchers::Routing
           end