4 files changed, 4 insertions, 0 deletions
diff --git a/test/lib/minitest/autorun.rb b/test/lib/minitest/autorun.rb
index 88b1e0550d..40640b2580 100644
--- a/test/lib/minitest/autorun.rb
+++ b/test/lib/minitest/autorun.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 begin
   require 'rubygems'
diff --git a/test/lib/minitest/benchmark.rb b/test/lib/minitest/benchmark.rb
index 5195fc01bc..21f0b29d50 100644
--- a/test/lib/minitest/benchmark.rb
+++ b/test/lib/minitest/benchmark.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'minitest/unit'
 
diff --git a/test/lib/minitest/mock.rb b/test/lib/minitest/mock.rb
index 19acaff68e..07e88113ea 100644
--- a/test/lib/minitest/mock.rb
+++ b/test/lib/minitest/mock.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 class MockExpectationError < StandardError; end # :nodoc:
 
diff --git a/test/lib/minitest/unit.rb b/test/lib/minitest/unit.rb
index e67ca02cd8..62f89e97e5 100644
--- a/test/lib/minitest/unit.rb
+++ b/test/lib/minitest/unit.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require "optparse"
 require "rbconfig"