diff --git a/Rakefile b/Rakefile
index 3fb75e0..fb81f6e 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'puppetlabs_spec_helper/rake_tasks'
 require 'puppet-lint/tasks/puppet-lint'
 require 'metadata-json-lint/rake_task'
diff --git a/spec/classes/config_spec.rb b/spec/classes/config_spec.rb
index 5b47dd8..ed90288 100644
--- a/spec/classes/config_spec.rb
+++ b/spec/classes/config_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'nuodb::config' do
diff --git a/spec/classes/init_spec.rb b/spec/classes/init_spec.rb
index 2042ae0..2064889 100644
--- a/spec/classes/init_spec.rb
+++ b/spec/classes/init_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'nuodb' do
diff --git a/spec/classes/install_spec.rb b/spec/classes/install_spec.rb
index d451c11..772e3f1 100644
--- a/spec/classes/install_spec.rb
+++ b/spec/classes/install_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'nuodb::install' do
diff --git a/spec/classes/service_spec.rb b/spec/classes/service_spec.rb
index 3374685..6838f4c 100644
--- a/spec/classes/service_spec.rb
+++ b/spec/classes/service_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'nuodb::service' do
diff --git a/spec/defines/database_spec.rb b/spec/defines/database_spec.rb
index 9e80e96..d2a11c7 100644
--- a/spec/defines/database_spec.rb
+++ b/spec/defines/database_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'nuodb::manager::database', type: :define do
diff --git a/spec/defines/domain_administrator_spec.rb b/spec/defines/domain_administrator_spec.rb
index 2740238..d06d927 100644
--- a/spec/defines/domain_administrator_spec.rb
+++ b/spec/defines/domain_administrator_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'nuodb::manager::domain_administrator', type: :define do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index ac66db9..045b555 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'puppetlabs_spec_helper/module_spec_helper'
 
 # /spec