7 files changed, 7 insertions, 0 deletions
diff --git a/ext/psych/lib/psych/nodes/alias.rb b/ext/psych/lib/psych/nodes/alias.rb
index 5bd4df13d1..716a00d62f 100644
--- a/ext/psych/lib/psych/nodes/alias.rb
+++ b/ext/psych/lib/psych/nodes/alias.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Nodes
     ###
diff --git a/ext/psych/lib/psych/nodes/document.rb b/ext/psych/lib/psych/nodes/document.rb
index 32014d60dc..7234fef1d8 100644
--- a/ext/psych/lib/psych/nodes/document.rb
+++ b/ext/psych/lib/psych/nodes/document.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Nodes
     ###
diff --git a/ext/psych/lib/psych/nodes/mapping.rb b/ext/psych/lib/psych/nodes/mapping.rb
index 5ba95ce4b6..4c11df8cd6 100644
--- a/ext/psych/lib/psych/nodes/mapping.rb
+++ b/ext/psych/lib/psych/nodes/mapping.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Nodes
     ###
diff --git a/ext/psych/lib/psych/nodes/node.rb b/ext/psych/lib/psych/nodes/node.rb
index 83233a61fd..e3621dc451 100644
--- a/ext/psych/lib/psych/nodes/node.rb
+++ b/ext/psych/lib/psych/nodes/node.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'stringio'
 require 'psych/class_loader'
 require 'psych/scalar_scanner'
diff --git a/ext/psych/lib/psych/nodes/scalar.rb b/ext/psych/lib/psych/nodes/scalar.rb
index 1b1b25b98a..ee5570518e 100644
--- a/ext/psych/lib/psych/nodes/scalar.rb
+++ b/ext/psych/lib/psych/nodes/scalar.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Nodes
     ###
diff --git a/ext/psych/lib/psych/nodes/sequence.rb b/ext/psych/lib/psych/nodes/sequence.rb
index 7e907fe2c8..1096469567 100644
--- a/ext/psych/lib/psych/nodes/sequence.rb
+++ b/ext/psych/lib/psych/nodes/sequence.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Nodes
     ###
diff --git a/ext/psych/lib/psych/nodes/stream.rb b/ext/psych/lib/psych/nodes/stream.rb
index 7cf5e033ec..559b0846e7 100644
--- a/ext/psych/lib/psych/nodes/stream.rb
+++ b/ext/psych/lib/psych/nodes/stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Psych
   module Nodes
     ###