diff --git a/activesupport/lib/active_support/testing/time_helpers.rb b/activesupport/lib/active_support/testing/time_helpers.rb
index 07c9be0604..3d9ff99729 100644
--- a/activesupport/lib/active_support/testing/time_helpers.rb
+++ b/activesupport/lib/active_support/testing/time_helpers.rb
@@ -1,4 +1,5 @@
 require "active_support/core_ext/string/strip" # for strip_heredoc
+require "active_support/core_ext/time/calculations"
 require "concurrent/map"
 
 module ActiveSupport