diff --git a/bin/git-generate-changelog b/bin/git-generate-changelog
index 5d0d48a..15a8d5e 100755
--- a/bin/git-generate-changelog
+++ b/bin/git-generate-changelog
@@ -1,4 +1,5 @@
 #! /usr/bin/env ruby
+# frozen_string_literal: true
 
 require_relative "../lib/github_changelog_generator"
 GitHubChangelogGenerator::ChangelogGenerator.new.run
diff --git a/bin/github_changelog_generator b/bin/github_changelog_generator
index 5d0d48a..15a8d5e 100755
--- a/bin/github_changelog_generator
+++ b/bin/github_changelog_generator
@@ -1,4 +1,5 @@
 #! /usr/bin/env ruby
+# frozen_string_literal: true
 
 require_relative "../lib/github_changelog_generator"
 GitHubChangelogGenerator::ChangelogGenerator.new.run
diff --git a/lib/github_changelog_generator.rb b/lib/github_changelog_generator.rb
index 3ef89bf..c478be5 100755
--- a/lib/github_changelog_generator.rb
+++ b/lib/github_changelog_generator.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 require "github_api"
 require "json"
diff --git a/lib/github_changelog_generator/fetcher.rb b/lib/github_changelog_generator/fetcher.rb
index c57fdd6..e1181bc 100644
--- a/lib/github_changelog_generator/fetcher.rb
+++ b/lib/github_changelog_generator/fetcher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module GitHubChangelogGenerator
   # A Fetcher responsible for all requests to GitHub and all basic manipulation with related data
   # (such as filtering, validating, e.t.c)
diff --git a/lib/github_changelog_generator/generator/generator.rb b/lib/github_changelog_generator/generator/generator.rb
index 68b6266..9f7a9bf 100644
--- a/lib/github_changelog_generator/generator/generator.rb
+++ b/lib/github_changelog_generator/generator/generator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../fetcher"
 require_relative "generator_generation"
 require_relative "generator_fetcher"
diff --git a/lib/github_changelog_generator/generator/generator_fetcher.rb b/lib/github_changelog_generator/generator/generator_fetcher.rb
index 6cc49f0..73c6de5 100644
--- a/lib/github_changelog_generator/generator/generator_fetcher.rb
+++ b/lib/github_changelog_generator/generator/generator_fetcher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module GitHubChangelogGenerator
   class Generator
     # Fetch event for issues and pull requests
diff --git a/lib/github_changelog_generator/generator/generator_generation.rb b/lib/github_changelog_generator/generator/generator_generation.rb
index 220d48c..62d7d50 100644
--- a/lib/github_changelog_generator/generator/generator_generation.rb
+++ b/lib/github_changelog_generator/generator/generator_generation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module GitHubChangelogGenerator
   class Generator
     # Main function to start change log generation
diff --git a/lib/github_changelog_generator/generator/generator_processor.rb b/lib/github_changelog_generator/generator/generator_processor.rb
index 7350791..ca03f6d 100644
--- a/lib/github_changelog_generator/generator/generator_processor.rb
+++ b/lib/github_changelog_generator/generator/generator_processor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module GitHubChangelogGenerator
   class Generator
     # delete all labels with labels from @options[:exclude_labels] array
diff --git a/lib/github_changelog_generator/generator/generator_tags.rb b/lib/github_changelog_generator/generator/generator_tags.rb
index 489c37c..c8dfc1c 100644
--- a/lib/github_changelog_generator/generator/generator_tags.rb
+++ b/lib/github_changelog_generator/generator/generator_tags.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module GitHubChangelogGenerator
   class Generator
     # fetch, filter tags, fetch dates and sort them in time order
diff --git a/lib/github_changelog_generator/helper.rb b/lib/github_changelog_generator/helper.rb
index 8da4be3..b529d36 100644
--- a/lib/github_changelog_generator/helper.rb
+++ b/lib/github_changelog_generator/helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "logger"
 require "rainbow"
 
diff --git a/lib/github_changelog_generator/parser.rb b/lib/github_changelog_generator/parser.rb
index e99fc7a..70dde2d 100755
--- a/lib/github_changelog_generator/parser.rb
+++ b/lib/github_changelog_generator/parser.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require "optparse"
 require "pp"
 require_relative "version"
diff --git a/lib/github_changelog_generator/parser_file.rb b/lib/github_changelog_generator/parser_file.rb
index 4f7bbfa..c13546c 100644
--- a/lib/github_changelog_generator/parser_file.rb
+++ b/lib/github_changelog_generator/parser_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "pathname"
 
 module GitHubChangelogGenerator
diff --git a/lib/github_changelog_generator/reader.rb b/lib/github_changelog_generator/reader.rb
index d0d65b2..4740003 100644
--- a/lib/github_changelog_generator/reader.rb
+++ b/lib/github_changelog_generator/reader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #
 # Author:: Enrico Stahn <mail@enricostahn.com>
 #
diff --git a/lib/github_changelog_generator/task.rb b/lib/github_changelog_generator/task.rb
index 4ff4bf5..72dd0b9 100644
--- a/lib/github_changelog_generator/task.rb
+++ b/lib/github_changelog_generator/task.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rake"
 require "rake/tasklib"
 require "github_changelog_generator"
diff --git a/lib/github_changelog_generator/version.rb b/lib/github_changelog_generator/version.rb
index 8d1f58e..979e916 100644
--- a/lib/github_changelog_generator/version.rb
+++ b/lib/github_changelog_generator/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module GitHubChangelogGenerator
   VERSION = "1.13.1"
 end