diff --git a/activesupport/lib/active_support/notifications/instrumenter.rb b/activesupport/lib/active_support/notifications/instrumenter.rb
index 7dfea4bb4b01e6dfa97db04fdfc40f62af2b6058..78d0397f1f0f01e184d1a29cc50f11aca5162706 100644
--- a/activesupport/lib/active_support/notifications/instrumenter.rb
+++ b/activesupport/lib/active_support/notifications/instrumenter.rb
@@ -1,3 +1,5 @@
+require 'securerandom'
+
 module ActiveSupport
   module Notifications
     # Instrumentors are stored in a thread local.