diff --git a/.travis.yml b/.travis.yml
index 16c08e7..5386d8c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,19 +5,13 @@ cache: bundler
 sudo: false
 
 rvm:
-  - 2.4.1
-  - 2.3.4
-  - 2.2.7
-  - 2.1
+  - 2.5.1
+  - 2.4.4
+  - 2.3.6
+  - 2.2.9
 
 gemfile:
+  - gemfiles/rails_5.2.gemfile
   - gemfiles/rails_5.1.gemfile
   - gemfiles/rails_5.0.gemfile
   - gemfiles/rails_4.2.gemfile
-
-matrix:
-  exclude:
-    - rvm: 2.1
-      gemfile: gemfiles/rails_5.0.gemfile
-    - rvm: 2.1
-      gemfile: gemfiles/rails_5.1.gemfile
diff --git a/Appraisals b/Appraisals
index b2ae2b6..c9fe20a 100644
--- a/Appraisals
+++ b/Appraisals
@@ -1,3 +1,7 @@
+appraise "rails-5.2" do
+  gem "rails", "~> 5.2.0"
+end
+
 appraise "rails-5.1" do
   gem "rails", "~> 5.1.0"
 end
diff --git a/MIT-LICENSE b/MIT-LICENSE
index b042913..938091c 100644
--- a/MIT-LICENSE
+++ b/MIT-LICENSE
@@ -1,4 +1,4 @@
-Copyright 2013-2017 Marc Anguera Insa
+Copyright 2013-2018 Marc Anguera Insa
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
diff --git a/gemfiles/rails_4.2.gemfile b/gemfiles/rails_4.2.gemfile
index dafebd6..7d0ac63 100644
--- a/gemfiles/rails_4.2.gemfile
+++ b/gemfiles/rails_4.2.gemfile
@@ -2,6 +2,6 @@
 
 source "https://rubygems.org"
 
-gem "rails", github: "rails/rails", branch: "4-2-stable"
+gem "rails", :github => "rails/rails", :branch => "4-2-stable"
 
-gemspec path: "../"
+gemspec :path => "../"
diff --git a/gemfiles/rails_5.0.gemfile b/gemfiles/rails_5.0.gemfile
index 10f52e7..123ad55 100644
--- a/gemfiles/rails_5.0.gemfile
+++ b/gemfiles/rails_5.0.gemfile
@@ -4,4 +4,4 @@ source "https://rubygems.org"
 
 gem "rails", "~> 5.0.0"
 
-gemspec path: "../"
+gemspec :path => "../"
diff --git a/gemfiles/rails_5.1.gemfile b/gemfiles/rails_5.1.gemfile
index 6100e83..20a05ff 100644
--- a/gemfiles/rails_5.1.gemfile
+++ b/gemfiles/rails_5.1.gemfile
@@ -4,4 +4,4 @@ source "https://rubygems.org"
 
 gem "rails", "~> 5.1.0"
 
-gemspec path: "../"
+gemspec :path => "../"
diff --git a/gemfiles/rails_5.2.gemfile b/gemfiles/rails_5.2.gemfile
new file mode 100644
index 0000000..0c9d569
--- /dev/null
+++ b/gemfiles/rails_5.2.gemfile
@@ -0,0 +1,7 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rails", "~> 5.2.0"
+
+gemspec :path => "../"
diff --git a/maily.gemspec b/maily.gemspec
index 73b27c3..8e235f5 100644
--- a/maily.gemspec
+++ b/maily.gemspec
@@ -19,6 +19,5 @@ Gem::Specification.new do |s|
 
   s.add_development_dependency "rspec-rails"
   s.add_development_dependency "appraisal"
-  s.add_development_dependency 'test-unit', '~> 3.0'
-  s.add_development_dependency "byebug" if RUBY_VERSION.to_i >= 2
+  s.add_development_dependency "byebug"
 end