6 files changed, 6 insertions, 0 deletions
diff --git a/ext/psych/lib/psych/visitors/depth_first.rb b/ext/psych/lib/psych/visitors/depth_first.rb
index c6eb814ac0..2d74a212d6 100644
--- a/ext/psych/lib/psych/visitors/depth_first.rb
+++ b/ext/psych/lib/psych/visitors/depth_first.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Visitors
     class DepthFirst < Psych::Visitors::Visitor
diff --git a/ext/psych/lib/psych/visitors/emitter.rb b/ext/psych/lib/psych/visitors/emitter.rb
index c886e5092e..f2ff9fdb28 100644
--- a/ext/psych/lib/psych/visitors/emitter.rb
+++ b/ext/psych/lib/psych/visitors/emitter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Visitors
     class Emitter < Psych::Visitors::Visitor
diff --git a/ext/psych/lib/psych/visitors/json_tree.rb b/ext/psych/lib/psych/visitors/json_tree.rb
index 0127ac8aa8..f2f0215cd2 100644
--- a/ext/psych/lib/psych/visitors/json_tree.rb
+++ b/ext/psych/lib/psych/visitors/json_tree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/json/ruby_events'
 
 module Psych
diff --git a/ext/psych/lib/psych/visitors/to_ruby.rb b/ext/psych/lib/psych/visitors/to_ruby.rb
index 4c3591b373..c061da25f1 100644
--- a/ext/psych/lib/psych/visitors/to_ruby.rb
+++ b/ext/psych/lib/psych/visitors/to_ruby.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/scalar_scanner'
 require 'psych/class_loader'
 require 'psych/exception'
diff --git a/ext/psych/lib/psych/visitors/visitor.rb b/ext/psych/lib/psych/visitors/visitor.rb
index 4d7772f428..d97bf550f6 100644
--- a/ext/psych/lib/psych/visitors/visitor.rb
+++ b/ext/psych/lib/psych/visitors/visitor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Visitors
     class Visitor
diff --git a/ext/psych/lib/psych/visitors/yaml_tree.rb b/ext/psych/lib/psych/visitors/yaml_tree.rb
index 6ad30d2683..e7c7a99060 100644
--- a/ext/psych/lib/psych/visitors/yaml_tree.rb
+++ b/ext/psych/lib/psych/visitors/yaml_tree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/tree_builder'
 require 'psych/scalar_scanner'
 require 'psych/class_loader'