diff --git a/test/irb/test_history.rb b/test/irb/test_history.rb
index bd03217fc..23242fa26 100644
--- a/test/irb/test_history.rb
+++ b/test/irb/test_history.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: false
 require 'test/unit'
+require 'irb'
 
 module TestIRB
   class TestHistory < Test::Unit::TestCase