diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index e4f8959e7a..cc96f158b5 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -1,4 +1,6 @@
 require 'rbconfig'
+require 'minitest/parallel_each'
+
 module ActiveSupport
   module Testing
     class RemoteError < StandardError