diff --git a/.travis.yml b/.travis.yml
index 182e74b90..42a28bc05 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,8 +3,6 @@ language: ruby
 sudo: false
 
 rvm:
-  - 2.1
-  - 2.2
   - 2.3
   - 2.4
   - 2.5
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c0f4dcb1..711757de5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## HEAD
 
+* Drop support for MRI 2.1 and 2.2 (@janko-m)
+
 * Fix `backgrounding` not working when default storage was changed with `Attachment.new` (@janko-m)
 
 * Don't clear existing metadata definitions when loading `add_metadata` plugin (@janko-m)
diff --git a/lib/shrine.rb b/lib/shrine.rb
index f8ae22033..97c64892f 100644
--- a/lib/shrine.rb
+++ b/lib/shrine.rb
@@ -33,7 +33,7 @@ def initialize(io, missing_methods)
     size:   [],
     close:  [],
   }
-  deprecate_constant(:IO_METHODS) if RUBY_VERSION > "2.3"
+  deprecate_constant(:IO_METHODS)
 
   @opts = {}
   @storages = {}
diff --git a/lib/shrine/plugins/_urlsafe_serialization.rb b/lib/shrine/plugins/_urlsafe_serialization.rb
index 3b2f9c6c8..5b1f8d1b1 100644
--- a/lib/shrine/plugins/_urlsafe_serialization.rb
+++ b/lib/shrine/plugins/_urlsafe_serialization.rb
@@ -121,14 +121,8 @@ def json_encode(data)
           JSON.generate(data)
         end
 
-        if RUBY_VERSION >= "2.3"
-          def base64_encode(data)
-            Base64.urlsafe_encode64(data, padding: false)
-          end
-        else
-          def base64_encode(data)
-            Base64.urlsafe_encode64(data)
-          end
+        def base64_encode(data)
+          Base64.urlsafe_encode64(data, padding: false)
         end
 
         def base64_decode(data)
diff --git a/lib/shrine/plugins/download_endpoint.rb b/lib/shrine/plugins/download_endpoint.rb
index bc6a4b01d..e47d80db1 100644
--- a/lib/shrine/plugins/download_endpoint.rb
+++ b/lib/shrine/plugins/download_endpoint.rb
@@ -132,7 +132,7 @@ def assign_download_endpoint(klass)
           @download_endpoint = endpoint_class
 
           const_set(:DownloadEndpoint, endpoint_class)
-          deprecate_constant(:DownloadEndpoint) if RUBY_VERSION > "2.3"
+          deprecate_constant(:DownloadEndpoint)
         end
       end
 
diff --git a/lib/shrine/plugins/presign_endpoint.rb b/lib/shrine/plugins/presign_endpoint.rb
index 5054f83d3..e1a3dc77d 100644
--- a/lib/shrine/plugins/presign_endpoint.rb
+++ b/lib/shrine/plugins/presign_endpoint.rb
@@ -138,14 +138,15 @@ module ClassMethods
         # Additional options can be given to override the options given on
         # plugin initialization.
         def presign_endpoint(storage_key, **options)
-          App.new({
+          App.new(
             shrine_class:     self,
             storage_key:      storage_key,
             presign_location: opts[:presign_endpoint_presign_location],
             presign_options:  opts[:presign_endpoint_presign_options],
             presign:          opts[:presign_endpoint_presign],
             rack_response:    opts[:presign_endpoint_rack_response],
-          }.merge(options))
+            **options
+          )
         end
       end
 
diff --git a/lib/shrine/plugins/rack_response.rb b/lib/shrine/plugins/rack_response.rb
index 3653351a1..7a0cebb82 100644
--- a/lib/shrine/plugins/rack_response.rb
+++ b/lib/shrine/plugins/rack_response.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require "rack"
-require "content_disposition" if RUBY_VERSION >= "2.3.0"
+require "content_disposition"
 
 class Shrine
   module Plugins
@@ -156,14 +156,8 @@ def parse_content_range(range_header)
           ranges.first if ranges && ranges.one?
         end
 
-        if RUBY_VERSION >= "2.3.0"
-          def content_disposition(disposition:, filename:)
-            ContentDisposition.format(disposition: disposition, filename: filename)
-          end
-        else
-          def content_disposition(disposition:, filename:)
-            "#{disposition}; filename=\"#{filename}\""
-          end
+        def content_disposition(disposition:, filename:)
+          ContentDisposition.format(disposition: disposition, filename: filename)
         end
 
         # Read size from metadata, otherwise retrieve the size from the storage.
diff --git a/lib/shrine/plugins/upload_endpoint.rb b/lib/shrine/plugins/upload_endpoint.rb
index d05324639..0cb853c8a 100644
--- a/lib/shrine/plugins/upload_endpoint.rb
+++ b/lib/shrine/plugins/upload_endpoint.rb
@@ -135,14 +135,15 @@ module ClassMethods
         # Additional options can be given to override the options given on
         # plugin initialization.
         def upload_endpoint(storage_key, **options)
-          App.new({
+          App.new(
             shrine_class:   self,
             storage_key:    storage_key,
             max_size:       opts[:upload_endpoint_max_size],
             upload_context: opts[:upload_endpoint_upload_context],
             upload:         opts[:upload_endpoint_upload],
             rack_response:  opts[:upload_endpoint_rack_response],
-          }.merge(options))
+            **options
+          )
         end
       end
 
diff --git a/lib/shrine/storage/s3.rb b/lib/shrine/storage/s3.rb
index 23bcfb9fb..8f5941e53 100644
--- a/lib/shrine/storage/s3.rb
+++ b/lib/shrine/storage/s3.rb
@@ -17,7 +17,7 @@
 end
 
 require "down/chunked_io"
-require "content_disposition" if RUBY_VERSION >= "2.3.0"
+require "content_disposition"
 
 require "uri"
 require "cgi"
@@ -353,7 +353,7 @@ def upload(io, id, shrine_metadata: {}, **upload_options)
 
         options = {}
         options[:content_type] = content_type if content_type
-        options[:content_disposition] = content_disposition(:inline, filename) if filename
+        options[:content_disposition] = ContentDisposition.inline(filename) if filename
         options[:acl] = "public-read" if public
 
         options.merge!(@upload_options)
@@ -606,16 +606,6 @@ def delete_objects(objects)
         end
       end
 
-      if RUBY_VERSION >= "2.3.0"
-        def content_disposition(disposition, filename)
-          ContentDisposition.format(disposition: disposition, filename: filename)
-        end
-      else
-        def content_disposition(disposition, filename)
-          "inline; filename=\"#{filename}\""
-        end
-      end
-
       # Upload requests will fail if filename has non-ASCII characters, because
       # of how S3 generates signatures, so we URI-encode them. Most browsers
       # should automatically URI-decode filenames when downloading.
diff --git a/lib/shrine/uploaded_file.rb b/lib/shrine/uploaded_file.rb
index cb4cd8018..eae9c6bd9 100644
--- a/lib/shrine/uploaded_file.rb
+++ b/lib/shrine/uploaded_file.rb
@@ -92,7 +92,7 @@ def mime_type
       #
       #     uploaded_file.open { |io| io.read } # the IO is automatically closed
       def open(*args)
-        @io.close if @io && !(@io.respond_to?(:closed?) && @io.closed?)
+        @io.close if @io
         @io = storage.open(id, *args)
 
         return @io unless block_given?
diff --git a/shrine.gemspec b/shrine.gemspec
index 9eac8a7fd..8a8c37c1b 100644
--- a/shrine.gemspec
+++ b/shrine.gemspec
@@ -4,7 +4,7 @@ Gem::Specification.new do |gem|
   gem.name         = "shrine"
   gem.version      = Shrine.version
 
-  gem.required_ruby_version = ">= 2.1"
+  gem.required_ruby_version = ">= 2.3"
 
   gem.summary      = "Toolkit for file attachments in Ruby applications"
   gem.description  = <<-END
@@ -27,7 +27,7 @@ direct uploads for fully asynchronous user experience.
   gem.require_path = "lib"
 
   gem.add_dependency "down", "~> 4.1"
-  gem.add_dependency "content_disposition", "~> 1.0" if RUBY_VERSION >= "2.3.0"
+  gem.add_dependency "content_disposition", "~> 1.0"
 
   gem.add_development_dependency "rake", ">= 11.1"
   gem.add_development_dependency "minitest", "~> 5.8"
@@ -37,11 +37,12 @@ direct uploads for fully asynchronous user experience.
   gem.add_development_dependency "shrine-memory", ">= 0.2.2"
 
   gem.add_development_dependency "roda"
-  gem.add_development_dependency "rack", (RUBY_VERSION >= "2.2.2" ? "~> 2.0" : "~> 1.6")
+  gem.add_development_dependency "rack", "~> 2.0"
   gem.add_development_dependency "mimemagic", ">= 0.3.2"
-  gem.add_development_dependency "marcel" if RUBY_VERSION >= "2.2.0"
+  gem.add_development_dependency "marcel"
   gem.add_development_dependency "mime-types"
   gem.add_development_dependency "mini_mime", "~> 1.0"
+  gem.add_development_dependency "ruby-filemagic", "~> 0.7" unless RUBY_ENGINE == "jruby" || ENV["CI"]
   gem.add_development_dependency "fastimage"
   gem.add_development_dependency "mini_magick", "~> 4.0" unless ENV["CI"]
   gem.add_development_dependency "ruby-vips", "~> 2.0" unless ENV["CI"]
@@ -49,20 +50,10 @@ direct uploads for fully asynchronous user experience.
   gem.add_development_dependency "aws-sdk-core", "~> 3.23"
   gem.add_development_dependency "http-form_data", "~> 2.0"
 
-  unless RUBY_ENGINE == "jruby" || ENV["CI"]
-    gem.add_development_dependency "ruby-filemagic", "~> 0.7"
-  end
-
   gem.add_development_dependency "sequel"
-
-  if RUBY_VERSION >= "2.2.2"
-    gem.add_development_dependency "activerecord", "~> 5.0"
-  else
-    gem.add_development_dependency "activerecord", "~> 4.2"
-  end
-
+  gem.add_development_dependency "activerecord", "~> 5.2.0"
   if RUBY_ENGINE == "jruby"
-    gem.add_development_dependency "activerecord-jdbcsqlite3-adapter", "51"
+    gem.add_development_dependency "activerecord-jdbcsqlite3-adapter", "~> 52.0"
   else
     gem.add_development_dependency "sqlite3"
   end
diff --git a/test/file_system_test.rb b/test/file_system_test.rb
index 5bb07d01f..08f509d85 100644
--- a/test/file_system_test.rb
+++ b/test/file_system_test.rb
@@ -124,7 +124,7 @@ def root_symlink
 
   describe "#movable?" do
     it "returns true for files and UploadedFiles from FileSystem" do
-      file                      = Tempfile.new("")
+      file                      = Tempfile.new
       file_system_uploaded_file = @shrine.new(:file_system).upload(fakeio)
       memory_uploaded_file      = @shrine.new(:memory).upload(fakeio)
       assert @storage.movable?(file, nil)
@@ -135,7 +135,7 @@ def root_symlink
 
   describe "#move" do
     it "moves files and UploadedFiles" do
-      file          = Tempfile.new("")
+      file          = Tempfile.new
       uploaded_file = @shrine.new(:file_system).upload(fakeio)
 
       @storage.move(file, "foo")
@@ -148,7 +148,7 @@ def root_symlink
     end
 
     it "creates subdirectories" do
-      file          = Tempfile.new("")
+      file          = Tempfile.new
       uploaded_file = @shrine.new(:file_system).upload(fakeio)
 
       @storage.move(file, "a/a/a.jpg")
@@ -166,18 +166,18 @@ def root_symlink
 
     it "sets file permissions" do
       @storage = file_system(root, permissions: 0600)
-      @storage.move(Tempfile.new(""), "bar.jpg")
+      @storage.move(Tempfile.new, "bar.jpg")
       assert_permissions 0600, @storage.open("bar.jpg").path
     end
 
     it "handles file permissions being nil" do
       @storage = file_system(root, permissions: nil)
-      @storage.move(Tempfile.new(""), "bar.jpg")
+      @storage.move(Tempfile.new, "bar.jpg")
     end
 
     it "sets directory permissions on intermediary directories" do
       @storage = file_system(root, directory_permissions: 0777)
-      @storage.move(Tempfile.new(""), "a/b/c/file.jpg")
+      @storage.move(Tempfile.new, "a/b/c/file.jpg")
       assert_permissions 0777, "#{root}/a"
       assert_permissions 0777, "#{root}/a/b"
       assert_permissions 0777, "#{root}/a/b/c"
@@ -185,7 +185,7 @@ def root_symlink
 
     it "handles directory permissions being nil" do
       @storage = file_system(root, directory_permissions: nil)
-      @storage.move(Tempfile.new(""), "a/b/c/file.jpg")
+      @storage.move(Tempfile.new, "a/b/c/file.jpg")
     end
   end
 
@@ -336,7 +336,7 @@ def root_symlink
     end
 
     deprecated "#download deletes the Tempfile if an error occurs while retrieving file contents" do
-      tempfile = Tempfile.new("")
+      tempfile = Tempfile.new
       Tempfile.stubs(:new).returns(tempfile)
       assert_raises(Errno::ENOENT) { @storage.download("foo") }
       assert tempfile.closed?
diff --git a/test/plugin/delete_raw_test.rb b/test/plugin/delete_raw_test.rb
index b4b4942a3..8cb0f6188 100644
--- a/test/plugin/delete_raw_test.rb
+++ b/test/plugin/delete_raw_test.rb
@@ -7,24 +7,24 @@
   end
 
   it "deletes files after upload" do
-    @uploader.upload(tempfile = Tempfile.new(""))
+    @uploader.upload(tempfile = Tempfile.new)
     refute File.exist?(tempfile.path)
   end
 
   it "deletes tempfiles after upload" do
-    @uploader.upload(file = File.open(Tempfile.new("").path))
+    @uploader.upload(file = File.open(Tempfile.new.path))
     refute File.exist?(file.path)
   end
 
   it "deletes IOs that respond to #path after upload" do
     io = FakeIO.new("file")
-    def io.path; (@tempfile ||= Tempfile.new("")).path; end
+    def io.path; (@tempfile ||= Tempfile.new).path; end
     @uploader.upload(io)
     refute File.exist?(io.path)
   end
 
   it "doesn't raise an error if file is already deleted" do
-    tempfile = Tempfile.new("")
+    tempfile = Tempfile.new
     File.delete(tempfile.path)
     @uploader.upload(tempfile)
   end
@@ -41,9 +41,9 @@ def io.path; (@tempfile ||= Tempfile.new("")).path; end
 
   it "accepts specifying storages" do
     @uploader.class.plugin :delete_raw, storages: [:store]
-    @uploader.class.new(:cache).upload(tempfile = Tempfile.new(""))
+    @uploader.class.new(:cache).upload(tempfile = Tempfile.new)
     assert File.exist?(tempfile.path)
-    @uploader.class.new(:store).upload(tempfile = Tempfile.new(""))
+    @uploader.class.new(:store).upload(tempfile = Tempfile.new)
     refute File.exist?(tempfile.path)
   end
 end
diff --git a/test/plugin/determine_mime_type_test.rb b/test/plugin/determine_mime_type_test.rb
index ab0f099ec..0a9f0df25 100644
--- a/test/plugin/determine_mime_type_test.rb
+++ b/test/plugin/determine_mime_type_test.rb
@@ -136,7 +136,7 @@
     it "returns nil for empty IOs" do
       assert_nil @shrine.determine_mime_type(fakeio(""))
     end
-  end if RUBY_VERSION >= "2.2.0"
+  end
 
   describe ":mime_types analyzer" do
     before do
diff --git a/test/plugin/download_endpoint_test.rb b/test/plugin/download_endpoint_test.rb
index 9df985a05..86796cffd 100644
--- a/test/plugin/download_endpoint_test.rb
+++ b/test/plugin/download_endpoint_test.rb
@@ -7,16 +7,6 @@ def app
     Rack::TestApp.wrap(Rack::Lint.new(@uploader.class.download_endpoint))
   end
 
-  if RUBY_VERSION >= "2.3.0"
-    def content_disposition(disposition, filename)
-      ContentDisposition.format(disposition: disposition, filename: filename)
-    end
-  else
-    def content_disposition(disposition, filename)
-      "#{disposition}; filename=\"#{filename}\""
-    end
-  end
-
   before do
     @uploader = uploader { plugin :download_endpoint }
     @shrine = @uploader.class
@@ -31,14 +21,14 @@ def content_disposition(disposition, filename)
     assert_equal @uploaded_file.read, response.body_binary
     assert_equal @uploaded_file.size.to_s, response.headers["Content-Length"]
     assert_equal @uploaded_file.mime_type, response.headers["Content-Type"]
-    assert_equal content_disposition(:inline, @uploaded_file.original_filename), response.headers["Content-Disposition"]
+    assert_equal ContentDisposition.inline(@uploaded_file.original_filename), response.headers["Content-Disposition"]
   end
 
   it "applies :disposition to response" do
     @uploader = uploader { plugin :download_endpoint, disposition: "attachment" }
     @uploaded_file = @uploader.upload(fakeio)
     response = app.get(@uploaded_file.download_url)
-    assert_equal content_disposition(:attachment, @uploaded_file.id), response.headers["Content-Disposition"]
+    assert_equal ContentDisposition.attachment(@uploaded_file.id), response.headers["Content-Disposition"]
   end
 
   it "returns Cache-Control" do
diff --git a/test/plugin/rack_file_test.rb b/test/plugin/rack_file_test.rb
index bde8b56c8..26da1a91a 100644
--- a/test/plugin/rack_file_test.rb
+++ b/test/plugin/rack_file_test.rb
@@ -8,7 +8,7 @@
     @shrine    = @attacher.shrine_class
     @rack_hash = {
       name: "file",
-      tempfile: Tempfile.new(""),
+      tempfile: Tempfile.new,
       filename: "image.jpg",
       type: "image/jpeg",
       head: "...",
diff --git a/test/plugin/rack_response_test.rb b/test/plugin/rack_response_test.rb
index 57dd4430d..5fd5be676 100644
--- a/test/plugin/rack_response_test.rb
+++ b/test/plugin/rack_response_test.rb
@@ -9,16 +9,6 @@
     @shrine = @uploader.class
   end
 
-  if RUBY_VERSION >= "2.3.0"
-    def content_disposition(disposition, filename)
-      ContentDisposition.format(disposition: disposition, filename: filename)
-    end
-  else
-    def content_disposition(disposition, filename)
-      "#{disposition}; filename=\"#{filename}\""
-    end
-  end
-
   it "returns 200 status" do
     uploaded_file = @uploader.upload(fakeio("content"))
     response = uploaded_file.to_rack_response
@@ -72,25 +62,25 @@ def content_disposition(disposition, filename)
   it "returns Content-Disposition filename from metadata" do
     uploaded_file = @uploader.upload(fakeio(filename: "plain.txt"))
     response = uploaded_file.to_rack_response
-    assert_equal content_disposition(:inline, "plain.txt"), response[1]["Content-Disposition"]
+    assert_equal ContentDisposition.inline("plain.txt"), response[1]["Content-Disposition"]
   end
 
   it "returns Content-Disposition filename from :filename" do
     uploaded_file = @uploader.upload(fakeio(filename: "plain.txt"))
     response = uploaded_file.to_rack_response(filename: "custom.txt")
-    assert_equal content_disposition(:inline, "custom.txt"), response[1]["Content-Disposition"]
+    assert_equal ContentDisposition.inline("custom.txt"), response[1]["Content-Disposition"]
   end
 
   it "returns Content-Disposition filename with id if metadata is missing" do
     uploaded_file = @uploader.upload(fakeio, location: "foo/bar/baz")
     response = uploaded_file.to_rack_response
-    assert_equal content_disposition(:inline, "baz"), response[1]["Content-Disposition"]
+    assert_equal ContentDisposition.inline("baz"), response[1]["Content-Disposition"]
   end
 
   it "returns Content-Disposition disposition from :disposition" do
     uploaded_file = @uploader.upload(fakeio)
     response = uploaded_file.to_rack_response(disposition: "attachment")
-    assert_equal content_disposition(:attachment, uploaded_file.id), response[1]["Content-Disposition"]
+    assert_equal ContentDisposition.attachment(uploaded_file.id), response[1]["Content-Disposition"]
   end
 
   it "returns body which yields contents of the file" do
diff --git a/test/s3_test.rb b/test/s3_test.rb
index 7acbfa9c1..0fa72ef0d 100644
--- a/test/s3_test.rb
+++ b/test/s3_test.rb
@@ -11,10 +11,7 @@
 
 describe Shrine::Storage::S3 do
   def s3(**options)
-    Shrine::Storage::S3.new({
-      bucket: "my-bucket",
-      stub_responses: true,
-    }.merge(options))
+    Shrine::Storage::S3.new(bucket: "my-bucket", stub_responses: true, **options)
   end
 
   before do
@@ -24,16 +21,6 @@ def s3(**options)
     @uploader = @shrine.new(:s3)
   end
 
-  if RUBY_VERSION >= "2.3.0"
-    def content_disposition(disposition, filename)
-      ContentDisposition.format(disposition: disposition, filename: filename)
-    end
-  else
-    def content_disposition(disposition, filename)
-      "#{disposition}; filename=\"#{filename}\""
-    end
-  end
-
   describe "#initialize" do
     it "raises an appropriate error when :bucket is nil" do
       error = assert_raises(ArgumentError) { s3(bucket: nil) }
@@ -365,7 +352,7 @@ def content_disposition(disposition, filename)
 
     it "forwards filename metadata" do
       @s3.upload(fakeio, "foo", shrine_metadata: { "filename" => "file.txt" })
-      assert_equal content_disposition(:inline, "file.txt"), @s3.client.api_requests[0][:params][:content_disposition]
+      assert_equal ContentDisposition.inline("file.txt"), @s3.client.api_requests[0][:params][:content_disposition]
     end
 
     deprecated "accepts :content_disposition with non-ASCII characters, quotes, and spaces" do
@@ -702,7 +689,7 @@ def content_disposition(disposition, filename)
 
       deprecated "deletes the Tempfile if an error occurs while retrieving file contents" do
         @s3.client.stub_responses(:get_object, "NetworkingError")
-        tempfile = Tempfile.new("")
+        tempfile = Tempfile.new
         Tempfile.stubs(:new).returns(tempfile)
         assert_raises(Aws::S3::Errors::NetworkingError) { @s3.download("foo") }
         assert tempfile.closed?
diff --git a/test/shrine_test.rb b/test/shrine_test.rb
index 876e9acb6..1d77d85db 100644
--- a/test/shrine_test.rb
+++ b/test/shrine_test.rb
@@ -126,7 +126,7 @@
     end
 
     it "yields Tempfile objects unchanged" do
-      tempfile = Tempfile.new("")
+      tempfile = Tempfile.new
       @shrine.with_file(tempfile) do |object|
         assert_equal tempfile, object
       end