diff --git a/.rubocop.yml b/.rubocop.yml
index 2564b28..592217c 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -207,8 +207,3 @@ Layout/IndentHeredoc:
   Enabled: false
 Layout/ClosingHeredocIndentation:
   Enabled: false
-
-# for rails 4 and ruby < 2.2.2
-Rails/HttpPositionalArguments:
-  Exclude:
-    - "spec/controllers/diaspora_federation/rails4_spec.rb"
diff --git a/.travis.yml b/.travis.yml
index 6622592..a805249 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,7 +8,6 @@ rvm:
   - 2.1
 gemfile:
   - Gemfile
-  - test/gemfiles/rails4.Gemfile
   - test/gemfiles/no-rails.Gemfile
 
 matrix:
diff --git a/Gemfile.lock b/Gemfile.lock
index 9ebdd4b..8ea0d9f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -9,7 +9,7 @@ PATH
       valid (~> 1.0)
     diaspora_federation-json_schema (0.2.6)
     diaspora_federation-rails (0.2.6)
-      actionpack (>= 4.2, < 6)
+      actionpack (>= 5, < 6)
       diaspora_federation (= 0.2.6)
     diaspora_federation-test (0.2.6)
       diaspora_federation (= 0.2.6)
diff --git a/diaspora_federation-rails.gemspec b/diaspora_federation-rails.gemspec
index edc4fba..66e08f3 100644
--- a/diaspora_federation-rails.gemspec
+++ b/diaspora_federation-rails.gemspec
@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = "~> 2.1"
 
-  s.add_dependency "actionpack", ">= 4.2", "< 6"
+  s.add_dependency "actionpack", ">= 5", "< 6"
 
   s.add_dependency "diaspora_federation", DiasporaFederation::VERSION
 end
diff --git a/lib/tasks/gemfiles.rake b/lib/tasks/gemfiles.rake
index 124f386..f50bf8f 100644
--- a/lib/tasks/gemfiles.rake
+++ b/lib/tasks/gemfiles.rake
@@ -1,5 +1,5 @@
 namespace :gemfiles do
-  desc "Generates rails4.Gemfile and no-rails.Gemfile"
+  desc "Generates no-rails.Gemfile"
   task :generate do
     FileUtils.mkdir_p("test/gemfiles")
     FileUtils.rm(Dir["test/gemfiles/*.Gemfile.lock"])
@@ -10,11 +10,6 @@ namespace :gemfiles do
     original_gemfile.sub!(/^group :development do$.*?^end$\n\n/m, "")
     original_gemfile << "\n gem \"fabrication\", \"< 2.17.0\"\n" # new versions are not compatible with ruby 2.1
 
-    rails4_version = "4.2.8"
-    rails4_gemfile = "#{original_gemfile}\ngem \"actionpack\", \"#{rails4_version}\"\n"
-    rails4_path = "test/gemfiles/rails4.Gemfile"
-    File.write(rails4_path, rails4_gemfile)
-
     no_rails_gemfile = original_gemfile.dup
     no_rails_gemfile.sub!(/(gemspec\(name:.*)/) { "#{Regexp.last_match[1]} unless plugin == \"rails\"" }
     no_rails_gemfile.sub!(/^.*rspec-rails.*$\n/, "")
@@ -22,7 +17,6 @@ namespace :gemfiles do
     File.write(no_rails_path, no_rails_gemfile)
 
     Bundler.with_clean_env do
-      system("BUNDLE_GEMFILE=#{rails4_path} bundle install")
       system("BUNDLE_GEMFILE=#{no_rails_path} bundle install")
     end
   end
diff --git a/spec/controllers/diaspora_federation/fetch_controller_spec.rb b/spec/controllers/diaspora_federation/fetch_controller_spec.rb
index 235783b..22916e9 100644
--- a/spec/controllers/diaspora_federation/fetch_controller_spec.rb
+++ b/spec/controllers/diaspora_federation/fetch_controller_spec.rb
@@ -1,5 +1,5 @@
 module DiasporaFederation
-  describe FetchController, type: :controller, rails: 5 do
+  describe FetchController, type: :controller do
     routes { DiasporaFederation::Engine.routes }
 
     let(:guid) { "12345678901234567890" }
diff --git a/spec/controllers/diaspora_federation/h_card_controller_spec.rb b/spec/controllers/diaspora_federation/h_card_controller_spec.rb
index 9ebbfd9..4bb4529 100644
--- a/spec/controllers/diaspora_federation/h_card_controller_spec.rb
+++ b/spec/controllers/diaspora_federation/h_card_controller_spec.rb
@@ -1,5 +1,5 @@
 module DiasporaFederation
-  describe HCardController, type: :controller, rails: 5 do
+  describe HCardController, type: :controller do
     routes { DiasporaFederation::Engine.routes }
 
     describe "GET #hcard" do
diff --git a/spec/controllers/diaspora_federation/rails4_spec.rb b/spec/controllers/diaspora_federation/rails4_spec.rb
deleted file mode 100644
index 7225c9a..0000000
--- a/spec/controllers/diaspora_federation/rails4_spec.rb
+++ /dev/null
@@ -1,81 +0,0 @@
-# only some basic controller tests for rails 4
-module DiasporaFederation
-  describe WebfingerController, type: :controller, rails: 4 do
-    routes { DiasporaFederation::Engine.routes }
-
-    it "contains the webfinger result" do
-      webfinger_xrd = DiasporaFederation::Discovery::WebFinger.new(
-        acct_uri:      "acct:#{alice.diaspora_id}",
-        alias_url:     alice.alias_url,
-        hcard_url:     alice.hcard_url,
-        seed_url:      alice.url,
-        profile_url:   alice.profile_url,
-        atom_url:      alice.atom_url,
-        salmon_url:    alice.salmon_url,
-        subscribe_url: alice.subscribe_url,
-        guid:          alice.guid,
-        public_key:    alice.serialized_public_key
-      ).to_xml
-
-      get :webfinger, format: :xml, resource: alice.diaspora_id
-      expect(response).to be_success
-      expect(response.body).to eq(webfinger_xrd)
-    end
-
-    it "404s when the person does not exist" do
-      get :webfinger, format: :xml, resource: "me@mydiaspora.pod.com"
-      expect(response).to be_not_found
-    end
-  end
-
-  describe HCardController, type: :controller, rails: 4 do
-    routes { DiasporaFederation::Engine.routes }
-
-    it "contains the hcard result" do
-      hcard_html = DiasporaFederation::Discovery::HCard.new(
-        guid:             alice.guid,
-        nickname:         alice.nickname,
-        full_name:        alice.full_name,
-        url:              alice.url,
-        photo_large_url:  alice.photo_default_url,
-        photo_medium_url: alice.photo_default_url,
-        photo_small_url:  alice.photo_default_url,
-        public_key:       alice.serialized_public_key,
-        searchable:       alice.searchable,
-        first_name:       alice.first_name,
-        last_name:        alice.last_name
-      ).to_html
-
-      get :hcard, guid: alice.guid
-      expect(response).to be_success
-      expect(response.body).to eq(hcard_html)
-    end
-
-    it "404s when the person does not exist" do
-      get :hcard, guid: "unknown_guid"
-      expect(response).to be_not_found
-    end
-  end
-
-  describe ReceiveController, type: :controller, rails: 4 do
-    routes { DiasporaFederation::Engine.routes }
-
-    describe "POST #public" do
-      it "returns a 202 if queued correctly" do
-        expect_callback(:queue_public_receive, "<diaspora/>", true)
-
-        post :public, xml: "<diaspora/>"
-        expect(response.code).to eq("202")
-      end
-    end
-
-    describe "POST #private" do
-      it "returns a 202 if the callback returned true" do
-        expect_callback(:queue_private_receive, "any-guid", "<diaspora/>", true).and_return(true)
-
-        post :private, guid: "any-guid", xml: "<diaspora/>"
-        expect(response.code).to eq("202")
-      end
-    end
-  end
-end
diff --git a/spec/controllers/diaspora_federation/receive_controller_spec.rb b/spec/controllers/diaspora_federation/receive_controller_spec.rb
index b480f48..281319e 100644
--- a/spec/controllers/diaspora_federation/receive_controller_spec.rb
+++ b/spec/controllers/diaspora_federation/receive_controller_spec.rb
@@ -15,21 +15,21 @@ module DiasporaFederation
           expect(response.code).to eq("422")
         end
 
-        it "returns a 202 if queued correctly", rails: 5 do
+        it "returns a 202 if queued correctly" do
           expect_callback(:queue_public_receive, "<diaspora/>", true)
 
           post :public, params: {xml: "<diaspora/>"}
           expect(response.code).to eq("202")
         end
 
-        it "unescapes the xml before sending it to the callback", rails: 5 do
+        it "unescapes the xml before sending it to the callback" do
           expect_callback(:queue_public_receive, "<diaspora/>", true)
 
           post :public, params: {xml: CGI.escape("<diaspora/>")}
         end
       end
 
-      context "magic envelope", rails: 5 do
+      context "magic envelope" do
         before do
           Mime::Type.register("application/magic-envelope+xml", :magic_envelope)
           @request.env["CONTENT_TYPE"] = "application/magic-envelope+xml"
@@ -44,7 +44,7 @@ module DiasporaFederation
       end
     end
 
-    describe "POST #private", rails: 5 do
+    describe "POST #private" do
       context "legacy salmon slap" do
         it "return a 404 if not queued successfully (unknown user guid)" do
           expect_callback(:queue_private_receive, "any-guid", "<diaspora/>", true).and_return(false)
diff --git a/spec/controllers/diaspora_federation/webfinger_controller_spec.rb b/spec/controllers/diaspora_federation/webfinger_controller_spec.rb
index b1796c6..335c19e 100644
--- a/spec/controllers/diaspora_federation/webfinger_controller_spec.rb
+++ b/spec/controllers/diaspora_federation/webfinger_controller_spec.rb
@@ -35,7 +35,7 @@ module DiasporaFederation
       end
     end
 
-    describe "GET #webfinger", rails: 5 do
+    describe "GET #webfinger" do
       it "uses the JRD format as default" do
         get :webfinger, params: {resource: alice.diaspora_id}
         expect(response).to be_successful
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index b4f4ce2..f7d6477 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -52,9 +52,7 @@ RSpec.configure do |config|
     expect_config.syntax = :expect
   end
 
-  if defined?(::Rails)
-    config.filter_run_excluding rails: (::Rails::VERSION::MAJOR == 5 ? 4 : 5)
-  else
+  unless defined?(::Rails)
     config.exclude_pattern = "**/controllers/**/*_spec.rb, **/routing/**/*_spec.rb"
     config.filter_run_excluding rails: true
   end
diff --git a/test/dummy/config/environments/test.rb b/test/dummy/config/environments/test.rb
index e7fbf43..6eee539 100644
--- a/test/dummy/config/environments/test.rb
+++ b/test/dummy/config/environments/test.rb
@@ -13,13 +13,8 @@ Rails.application.configure do
   config.eager_load = false
 
   # Configure static file server for tests with Cache-Control for performance.
-  if Rails::VERSION::MAJOR == 5
-    config.public_file_server.enable  = true
-    config.public_file_server.headers = {"Cache-Control" => "public, max-age=3600"}
-  else
-    config.serve_static_files   = true
-    config.static_cache_control = "public, max-age=3600"
-  end
+  config.public_file_server.enable  = true
+  config.public_file_server.headers = {"Cache-Control" => "public, max-age=3600"}
 
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
diff --git a/test/gemfiles/rails4.Gemfile b/test/gemfiles/rails4.Gemfile
deleted file mode 100644
index 8de5931..0000000
--- a/test/gemfiles/rails4.Gemfile
+++ /dev/null
@@ -1,44 +0,0 @@
-source "https://rubygems.org"
-
-# Declare your gem's dependencies in diaspora_federation.gemspec.
-# Bundler will treat runtime dependencies like base dependencies, and
-# development dependencies will be added by default to the :development group.
-gemspec name: "diaspora_federation", path: "../../"
-
-Dir["diaspora_federation-*.gemspec"].each do |gemspec|
-  plugin = gemspec.scan(/diaspora_federation-(.*)\.gemspec/).flatten.first
-  gemspec(name: "diaspora_federation-#{plugin}", development_group: plugin, path: "../../")
-end
-
-# Declare any dependencies that are still in development here instead of in
-# your gemspec. These might include edge Rails or gems from your path or
-# Git. Remember to move these dependencies to your gemspec before releasing
-# your gem to rubygems.org.
-
-group :test do
-  # rspec formatter
-  gem "fuubar", "2.3.2",    require: false
-  gem "nyan-cat-formatter", require: false
-
-  # test coverage
-  gem "simplecov",                 "0.16.1",   require: false
-  gem "simplecov-rcov",            "0.2.3",    require: false
-
-  # test helpers
-  gem "json-schema-rspec", "0.0.4"
-  gem "rspec-collection_matchers", "~> 1.1.2"
-  gem "rspec-json_expectations",   "~> 2.1"
-  gem "webmock",                   "~> 3.0"
-end
-
-group :development, :test do
-  gem "rake"
-
-  # unit tests
-  gem "rspec", "~> 3.8.0"
-  gem "rspec-rails", "~> 3.8.0"
-end
-
- gem "fabrication", "< 2.17.0"
-
-gem "actionpack", "4.2.8"
diff --git a/test/gemfiles/rails4.Gemfile.lock b/test/gemfiles/rails4.Gemfile.lock
deleted file mode 100644
index 917f535..0000000
--- a/test/gemfiles/rails4.Gemfile.lock
+++ /dev/null
@@ -1,171 +0,0 @@
-PATH
-  remote: ../..
-  specs:
-    diaspora_federation (0.2.6)
-      faraday (>= 0.9.0, < 0.16.0)
-      faraday_middleware (>= 0.10.0, < 0.14.0)
-      nokogiri (~> 1.6, >= 1.6.8)
-      typhoeus (~> 1.0)
-      valid (~> 1.0)
-    diaspora_federation-json_schema (0.2.6)
-    diaspora_federation-rails (0.2.6)
-      actionpack (>= 4.2, < 6)
-      diaspora_federation (= 0.2.6)
-    diaspora_federation-test (0.2.6)
-      diaspora_federation (= 0.2.6)
-      fabrication (~> 2.16)
-      uuid (~> 2.3, >= 2.3.8)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-    actionpack (4.2.8)
-      actionview (= 4.2.8)
-      activesupport (= 4.2.8)
-      rack (~> 1.6)
-      rack-test (~> 0.6.2)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (4.2.8)
-      activesupport (= 4.2.8)
-      builder (~> 3.1)
-      erubis (~> 2.7.0)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.3)
-    activesupport (4.2.8)
-      i18n (~> 0.7)
-      minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
-      tzinfo (~> 1.1)
-    addressable (2.6.0)
-      public_suffix (>= 2.0.2, < 4.0)
-    builder (3.2.3)
-    concurrent-ruby (1.1.5)
-    crack (0.4.3)
-      safe_yaml (~> 1.0.0)
-    crass (1.0.4)
-    diff-lcs (1.3)
-    docile (1.3.1)
-    erubis (2.7.0)
-    ethon (0.12.0)
-      ffi (>= 1.3.0)
-    fabrication (2.16.3)
-    faraday (0.15.4)
-      multipart-post (>= 1.2, < 3)
-    faraday_middleware (0.13.1)
-      faraday (>= 0.7.4, < 1.0)
-    ffi (1.10.0)
-    fuubar (2.3.2)
-      rspec-core (~> 3.0)
-      ruby-progressbar (~> 1.4)
-    hashdiff (0.3.8)
-    i18n (0.9.5)
-      concurrent-ruby (~> 1.0)
-    json (2.2.0)
-    json-schema (2.8.1)
-      addressable (>= 2.4)
-    json-schema-rspec (0.0.4)
-      json-schema (~> 2.5)
-      rspec
-    loofah (2.2.3)
-      crass (~> 1.0.2)
-      nokogiri (>= 1.5.9)
-    macaddr (1.7.1)
-      systemu (~> 2.6.2)
-    mini_portile2 (2.4.0)
-    minitest (5.11.3)
-    multipart-post (2.0.0)
-    nokogiri (1.9.1)
-      mini_portile2 (~> 2.4.0)
-    nyan-cat-formatter (0.12.0)
-      rspec (>= 2.99, >= 2.14.2, < 4)
-    public_suffix (3.0.3)
-    rack (1.6.11)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails-deprecated_sanitizer (1.0.3)
-      activesupport (>= 4.2.0.alpha)
-    rails-dom-testing (1.0.9)
-      activesupport (>= 4.2.0, < 5.0)
-      nokogiri (~> 1.6)
-      rails-deprecated_sanitizer (>= 1.0.1)
-    rails-html-sanitizer (1.0.4)
-      loofah (~> 2.2, >= 2.2.2)
-    railties (4.2.8)
-      actionpack (= 4.2.8)
-      activesupport (= 4.2.8)
-      rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (12.3.2)
-    rspec (3.8.0)
-      rspec-core (~> 3.8.0)
-      rspec-expectations (~> 3.8.0)
-      rspec-mocks (~> 3.8.0)
-    rspec-collection_matchers (1.1.3)
-      rspec-expectations (>= 2.99.0.beta1)
-    rspec-core (3.8.0)
-      rspec-support (~> 3.8.0)
-    rspec-expectations (3.8.2)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
-    rspec-json_expectations (2.1.0)
-    rspec-mocks (3.8.0)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
-    rspec-rails (3.8.2)
-      actionpack (>= 3.0)
-      activesupport (>= 3.0)
-      railties (>= 3.0)
-      rspec-core (~> 3.8.0)
-      rspec-expectations (~> 3.8.0)
-      rspec-mocks (~> 3.8.0)
-      rspec-support (~> 3.8.0)
-    rspec-support (3.8.0)
-    ruby-progressbar (1.10.0)
-    safe_yaml (1.0.5)
-    simplecov (0.16.1)
-      docile (~> 1.1)
-      json (>= 1.8, < 3)
-      simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.2)
-    simplecov-rcov (0.2.3)
-      simplecov (>= 0.4.1)
-    systemu (2.6.5)
-    thor (0.20.3)
-    thread_safe (0.3.6)
-    typhoeus (1.3.1)
-      ethon (>= 0.9.0)
-    tzinfo (1.2.5)
-      thread_safe (~> 0.1)
-    uuid (2.3.9)
-      macaddr (~> 1.0)
-    valid (1.2.0)
-    webmock (3.5.1)
-      addressable (>= 2.3.6)
-      crack (>= 0.3.2)
-      hashdiff
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  actionpack (= 4.2.8)
-  diaspora_federation!
-  diaspora_federation-json_schema!
-  diaspora_federation-rails!
-  diaspora_federation-test!
-  fabrication (< 2.17.0)
-  fuubar (= 2.3.2)
-  json-schema-rspec (= 0.0.4)
-  nyan-cat-formatter
-  rake
-  rspec (~> 3.8.0)
-  rspec-collection_matchers (~> 1.1.2)
-  rspec-json_expectations (~> 2.1)
-  rspec-rails (~> 3.8.0)
-  simplecov (= 0.16.1)
-  simplecov-rcov (= 0.2.3)
-  webmock (~> 3.0)
-
-BUNDLED WITH
-   1.17.3