diff --git a/test/irb/helper.rb b/test/irb/helper.rb
index 44dd41bd1..650b95d8f 100644
--- a/test/irb/helper.rb
+++ b/test/irb/helper.rb
@@ -79,7 +79,7 @@ def without_rdoc(&block)
     end
   end
 
-  class IntegrationTestCase
+  class IntegrationTestCase < TestCase
     LIB = File.expand_path("../../lib", __dir__)
     TIMEOUT_SEC = 3