diff --git a/lib/gitlab/ci/external/file/base.rb b/lib/gitlab/ci/external/file/base.rb
index 4591b3ec82e..f4da07b0b02 100644
--- a/lib/gitlab/ci/external/file/base.rb
+++ b/lib/gitlab/ci/external/file/base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module External
diff --git a/lib/gitlab/ci/external/file/local.rb b/lib/gitlab/ci/external/file/local.rb
index 829cc9b3d19..1aa7f687507 100644
--- a/lib/gitlab/ci/external/file/local.rb
+++ b/lib/gitlab/ci/external/file/local.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module External
diff --git a/lib/gitlab/ci/external/file/remote.rb b/lib/gitlab/ci/external/file/remote.rb
index b4294231265..59bb3e8999e 100644
--- a/lib/gitlab/ci/external/file/remote.rb
+++ b/lib/gitlab/ci/external/file/remote.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module External
diff --git a/lib/gitlab/ci/external/mapper.rb b/lib/gitlab/ci/external/mapper.rb
index 3c359efa803..58bd6a19acf 100644
--- a/lib/gitlab/ci/external/mapper.rb
+++ b/lib/gitlab/ci/external/mapper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module External
diff --git a/lib/gitlab/ci/external/processor.rb b/lib/gitlab/ci/external/processor.rb
index 22588867a08..76cf3ce89f9 100644
--- a/lib/gitlab/ci/external/processor.rb
+++ b/lib/gitlab/ci/external/processor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module External
diff --git a/spec/lib/gitlab/ci/external/file/local_spec.rb b/spec/lib/gitlab/ci/external/file/local_spec.rb
index a4099703ac9..3f32d81a827 100644
--- a/spec/lib/gitlab/ci/external/file/local_spec.rb
+++ b/spec/lib/gitlab/ci/external/file/local_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::Ci::External::File::Local do
diff --git a/spec/lib/gitlab/ci/external/file/remote_spec.rb b/spec/lib/gitlab/ci/external/file/remote_spec.rb
index 314dcfec511..b1819c8960b 100644
--- a/spec/lib/gitlab/ci/external/file/remote_spec.rb
+++ b/spec/lib/gitlab/ci/external/file/remote_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::Ci::External::File::Remote do
diff --git a/spec/lib/gitlab/ci/external/mapper_spec.rb b/spec/lib/gitlab/ci/external/mapper_spec.rb
index 89285c8ba45..6270d27a36d 100644
--- a/spec/lib/gitlab/ci/external/mapper_spec.rb
+++ b/spec/lib/gitlab/ci/external/mapper_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::Ci::External::Mapper do
diff --git a/spec/lib/gitlab/ci/external/processor_spec.rb b/spec/lib/gitlab/ci/external/processor_spec.rb
index bf355ddb21d..688c2b3c8aa 100644
--- a/spec/lib/gitlab/ci/external/processor_spec.rb
+++ b/spec/lib/gitlab/ci/external/processor_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::Ci::External::Processor do