diff --git a/test/json/test_helper.rb b/test/json/test_helper.rb
index 10478aef7e..4955a02c9d 100644
--- a/test/json/test_helper.rb
+++ b/test/json/test_helper.rb
@@ -15,3 +15,8 @@ begin
   require 'byebug'
 rescue LoadError
 end
+
+unless defined?(Test::Unit::CoreAssertions)
+  require "core_assertions"
+  Test::Unit::TestCase.include Test::Unit::CoreAssertions
+end