diff --git a/lib/irb/ruby-lex.rb b/lib/irb/ruby-lex.rb
index d5630c8b52..0c71d5ec03 100644
--- a/lib/irb/ruby-lex.rb
+++ b/lib/irb/ruby-lex.rb
@@ -11,6 +11,7 @@
 #
 
 require "ripper"
+require "jruby" if RUBY_ENGINE == "jruby"
 
 # :stopdoc:
 class RubyLex