diff --git a/lib/optparse/ac.rb b/lib/optparse/ac.rb
index 9d52010..0953725 100644
--- a/lib/optparse/ac.rb
+++ b/lib/optparse/ac.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: false
-require 'optparse'
+require_relative '../optparse'
 
 class OptionParser::AC < OptionParser
   private
diff --git a/lib/optparse/date.rb b/lib/optparse/date.rb
index d6649c8..7bbf12b 100644
--- a/lib/optparse/date.rb
+++ b/lib/optparse/date.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: false
-require 'optparse'
+require_relative '../optparse'
 require 'date'
 
 OptionParser.accept(DateTime) do |s,|
diff --git a/lib/optparse/kwargs.rb b/lib/optparse/kwargs.rb
index ccf20c6..992aca4 100644
--- a/lib/optparse/kwargs.rb
+++ b/lib/optparse/kwargs.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
-require 'optparse'
+require_relative '../optparse'
 
 class OptionParser
   # :call-seq:
diff --git a/lib/optparse/shellwords.rb b/lib/optparse/shellwords.rb
index bf31701..4feb199 100644
--- a/lib/optparse/shellwords.rb
+++ b/lib/optparse/shellwords.rb
@@ -2,6 +2,6 @@
 # -*- ruby -*-
 
 require 'shellwords'
-require 'optparse'
+require_relative '../optparse'
 
 OptionParser.accept(Shellwords) {|s,| Shellwords.shellwords(s)}
diff --git a/lib/optparse/time.rb b/lib/optparse/time.rb
index ffc6ff0..0ce651f 100644
--- a/lib/optparse/time.rb
+++ b/lib/optparse/time.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: false
-require 'optparse'
+require_relative '../optparse'
 require 'time'
 
 OptionParser.accept(Time) do |s,|
diff --git a/lib/optparse/uri.rb b/lib/optparse/uri.rb
index 51550cf..31d1059 100644
--- a/lib/optparse/uri.rb
+++ b/lib/optparse/uri.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: false
 # -*- ruby -*-
 
-require 'optparse'
+require_relative '../optparse'
 require 'uri'
 
 OptionParser.accept(URI) {|s,| URI.parse(s) if s}