diff --git a/lib/reline/ansi.rb b/lib/reline/ansi.rb
index c7c74ccb90..3880f51551 100644
--- a/lib/reline/ansi.rb
+++ b/lib/reline/ansi.rb
@@ -1,4 +1,5 @@
 require 'io/console'
+require 'io/wait'
 require 'timeout'
 require_relative 'terminfo'