diff --git a/app/models/group.rb b/app/models/group.rb
index 46710b6..3738e97 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Group < ApplicationRecord
   belongs_to :matches
   belongs_to :teams
diff --git a/app/models/group_stage.rb b/app/models/group_stage.rb
index 326fd4e..aac2290 100644
--- a/app/models/group_stage.rb
+++ b/app/models/group_stage.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class GroupStage < ApplicationRecord
 end
diff --git a/app/models/match.rb b/app/models/match.rb
index ea72ed7..5d8cb6e 100644
--- a/app/models/match.rb
+++ b/app/models/match.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Match < ApplicationRecord
 end
diff --git a/app/models/playoff_stage.rb b/app/models/playoff_stage.rb
index 24bfaf9..682ef29 100644
--- a/app/models/playoff_stage.rb
+++ b/app/models/playoff_stage.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class PlayoffStage < ApplicationRecord
 end
diff --git a/app/models/team.rb b/app/models/team.rb
index 48a6c83..ab022b6 100644
--- a/app/models/team.rb
+++ b/app/models/team.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class Team < ApplicationRecord
 end
diff --git a/db/migrate/20181111174658_create_groups.rb b/db/migrate/20181111174658_create_groups.rb
index f645ff3..67fc96b 100644
--- a/db/migrate/20181111174658_create_groups.rb
+++ b/db/migrate/20181111174658_create_groups.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateGroups < ActiveRecord::Migration[5.2]
   def change
     create_table :groups do |t|
diff --git a/db/migrate/20181111174759_create_group_stages.rb b/db/migrate/20181111174759_create_group_stages.rb
index fa3650c..97d0dd8 100644
--- a/db/migrate/20181111174759_create_group_stages.rb
+++ b/db/migrate/20181111174759_create_group_stages.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateGroupStages < ActiveRecord::Migration[5.2]
   def change
     create_table :group_stages do |t|
diff --git a/db/migrate/20181111174944_create_matches.rb b/db/migrate/20181111174944_create_matches.rb
index 5e8bbe1..9c865a8 100644
--- a/db/migrate/20181111174944_create_matches.rb
+++ b/db/migrate/20181111174944_create_matches.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateMatches < ActiveRecord::Migration[5.2]
   def change
     create_table :matches do |t|
diff --git a/db/migrate/20181111175026_create_playoff_stages.rb b/db/migrate/20181111175026_create_playoff_stages.rb
index 5ca4d03..4842611 100644
--- a/db/migrate/20181111175026_create_playoff_stages.rb
+++ b/db/migrate/20181111175026_create_playoff_stages.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreatePlayoffStages < ActiveRecord::Migration[5.2]
   def change
     create_table :playoff_stages do |t|
diff --git a/db/migrate/20181111175127_create_teams.rb b/db/migrate/20181111175127_create_teams.rb
index 07f1f27..c1a1e8a 100644
--- a/db/migrate/20181111175127_create_teams.rb
+++ b/db/migrate/20181111175127_create_teams.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateTeams < ActiveRecord::Migration[5.2]
   def change
     create_table :teams do |t|
diff --git a/test/models/group_stage_test.rb b/test/models/group_stage_test.rb
index d9d6197..419f8f1 100644
--- a/test/models/group_stage_test.rb
+++ b/test/models/group_stage_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class GroupStageTest < ActiveSupport::TestCase
diff --git a/test/models/group_test.rb b/test/models/group_test.rb
index 778eb0c..ae91507 100644
--- a/test/models/group_test.rb
+++ b/test/models/group_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class GroupTest < ActiveSupport::TestCase
diff --git a/test/models/match_test.rb b/test/models/match_test.rb
index 14436b1..5355c36 100644
--- a/test/models/match_test.rb
+++ b/test/models/match_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class MatchTest < ActiveSupport::TestCase
diff --git a/test/models/playoff_stage_test.rb b/test/models/playoff_stage_test.rb
index c1da24e..99dd86c 100644
--- a/test/models/playoff_stage_test.rb
+++ b/test/models/playoff_stage_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class PlayoffStageTest < ActiveSupport::TestCase
diff --git a/test/models/team_test.rb b/test/models/team_test.rb
index 8b101cb..edf6534 100644
--- a/test/models/team_test.rb
+++ b/test/models/team_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class TeamTest < ActiveSupport::TestCase