diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index cc96f158b5..dca91e8b75 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -1,5 +1,8 @@
 require 'rbconfig'
-require 'minitest/parallel_each'
+begin
+  require 'minitest/parallel_each'
+rescue LoadError
+end
 
 module ActiveSupport
   module Testing