diff --git a/test/unit/tedrahcu_test.rb b/test/unit/tedrahcu_test.rb
index a592eff..9c2bfd3 100644
--- a/test/unit/tedrahcu_test.rb
+++ b/test/unit/tedrahcu_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative '../preamble'
 
 class TedrahcuTest < Minitest::Test