diff --git a/lib/optparse.rb b/lib/optparse.rb
index d52401a31b..50641867f0 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -1115,7 +1115,7 @@ XXX
     Switch::OptionalArgument.new do |pkg|
       if pkg
         begin
-          require 'optparse/version'
+          require_relative 'optparse/version'
         rescue LoadError
         else
           show_version(*pkg.split(/,/)) or