6 files changed, 6 insertions, 0 deletions
diff --git a/lib/optparse/ac.rb b/lib/optparse/ac.rb
index 6a8626094d..fb0883f97a 100644
--- a/lib/optparse/ac.rb
+++ b/lib/optparse/ac.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 
 class OptionParser::AC < OptionParser
diff --git a/lib/optparse/date.rb b/lib/optparse/date.rb
index d680559f37..d6649c83f1 100644
--- a/lib/optparse/date.rb
+++ b/lib/optparse/date.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 require 'date'
 
diff --git a/lib/optparse/shellwords.rb b/lib/optparse/shellwords.rb
index 0422d7c887..bf31701b96 100644
--- a/lib/optparse/shellwords.rb
+++ b/lib/optparse/shellwords.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 
 require 'shellwords'
diff --git a/lib/optparse/time.rb b/lib/optparse/time.rb
index 402cadcf16..ffc6ff000d 100644
--- a/lib/optparse/time.rb
+++ b/lib/optparse/time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 require 'time'
 
diff --git a/lib/optparse/uri.rb b/lib/optparse/uri.rb
index 024dc69eac..51550cf91b 100644
--- a/lib/optparse/uri.rb
+++ b/lib/optparse/uri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 
 require 'optparse'
diff --git a/lib/optparse/version.rb b/lib/optparse/version.rb
index 8525677418..b869d8fe51 100644
--- a/lib/optparse/version.rb
+++ b/lib/optparse/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # OptionParser internal utility
 
 class << OptionParser