diff --git a/spec/dummy/config/application.rb b/spec/dummy/config/application.rb
index e390493e..7af3fdc1 100644
--- a/spec/dummy/config/application.rb
+++ b/spec/dummy/config/application.rb
@@ -8,6 +8,14 @@
 Bundler.require(*Rails.groups)
 require "govuk/components"
 
+module Sprockets
+  module Rails
+    def self.deprecator
+      @deprecator ||= ActiveSupport::Deprecation.new("4.0", "Sprockets::Rails")
+    end
+  end
+end
+
 module Dummy
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.