diff --git a/Rakefile b/Rakefile
index 4b9260b..3582859 100644
--- a/Rakefile
+++ b/Rakefile
@@ -19,7 +19,7 @@ Rake::TestTask.new(:test) do |t|
 end
 
 desc 'Start an IRB session with all necessary files required.'
-task :shell do |t|
+task :shell do
   chdir File.dirname(__FILE__)
   exec 'irb -I lib/ -I lib/paperclip -r rubygems -r active_record -r tempfile -r init'
 end
@@ -39,7 +39,7 @@ task :sync_docs => 'rdoc' do
 end
 
 desc 'Clean up files.'
-task :clean do |t|
+task :clean do
   FileUtils.rm_rf "doc"
   FileUtils.rm_rf "tmp"
   FileUtils.rm_rf "pkg"
diff --git a/lib/paperclip/storage/no_cache_s3.rb b/lib/paperclip/storage/no_cache_s3.rb
index e8d8653..d92444e 100644
--- a/lib/paperclip/storage/no_cache_s3.rb
+++ b/lib/paperclip/storage/no_cache_s3.rb
@@ -142,7 +142,7 @@ module Paperclip
           (self.class.store_ids - [self.class.main_store_id]).each { |store_id| enqueue_sync_job(store_id) }
         end
         # HACK: Iostream пишет в tempfile, и он нигде не закрывается. Будем закрывать хотя бы тут
-        if queued_for_write[:original]&.is_a?(Tempfile)
+        if queued_for_write[:original].is_a?(Tempfile)
           queued_for_write[:original].close
           queued_for_write[:original].unlink
         end
diff --git a/paperclip.gemspec b/paperclip.gemspec
index 56ab4ac..6d03eb2 100644
--- a/paperclip.gemspec
+++ b/paperclip.gemspec
@@ -8,9 +8,9 @@ Gem::Specification.new do |s|
   s.date = %q{2009-06-18}
   s.email = %q{jyurek@thoughtbot.com}
   s.extra_rdoc_files = ["README.rdoc"]
-  s.files = `git ls-files -z`.split("\x0").reject do |f|
-    f.start_with?('.') || f.match?(%r{^(test|gemfiles)/}) ||
-      f.match?(%r{docker-compose.yml|Appraisals|Gemfile|Rakefile})
+  s.files = `git ls-files -z`.split("\x0").reject do |file|
+    file.start_with?('.') || file.match?(%r{^(test|gemfiles)/}) ||
+      file.match?(/docker-compose.yml|Appraisals|Gemfile|Rakefile/)
   end
   s.homepage = %q{http://www.thoughtbot.com/projects/paperclip}
   s.rdoc_options = ["--line-numbers", "--inline-source"]
diff --git a/test/attachment_test.rb b/test/attachment_test.rb
index 6f2efb1..b602b70 100644
--- a/test/attachment_test.rb
+++ b/test/attachment_test.rb
@@ -153,9 +153,10 @@ class AttachmentTest < Test::Unit::TestCase
     end
   end
 
+  class Paperclip::Test < Paperclip::Processor; end
+
   context "An attachment with multiple processors" do
     setup do
-      class Paperclip::Test < Paperclip::Processor; end
       @style_params = { :once => {:one => 1, :two => 2} }
       rebuild_model :processors => [:thumbnail, :test], :styles => @style_params
       @dummy = Dummy.new
@@ -345,7 +346,7 @@ class AttachmentTest < Test::Unit::TestCase
                [:small, 32, 32, "JPEG"]].each do |style|
                 cmd = %Q[identify -format "%w %h %b %m" "#{@attachment.path(style.first)}"]
                 out = `#{cmd}`
-                width, height, size, format = out.split(" ")
+                width, height, _size, format = out.split(" ")
                 assert_equal style[1].to_s, width.to_s
                 assert_equal style[2].to_s, height.to_s
                 assert_equal style[3].to_s, format.to_s
diff --git a/test/integration_test.rb b/test/integration_test.rb
index 25f83cc..16ae117 100644
--- a/test/integration_test.rb
+++ b/test/integration_test.rb
@@ -6,9 +6,9 @@ class IntegrationTest < Test::Unit::TestCase
   context "Many models at once" do
     setup do
       rebuild_model
-      @file      = File.new(File.join(FIXTURES_DIR, "5k.png"), 'rb')
-      300.times do |i|
-        Dummy.create! :avatar => @file
+      @file = File.new(File.join(FIXTURES_DIR, "5k.png"), 'rb')
+      300.times do
+        Dummy.create! avatar: @file
       end
     end
 
@@ -33,7 +33,7 @@ class IntegrationTest < Test::Unit::TestCase
     teardown { @file.close }
 
     should "create its thumbnails properly" do
-      assert_match /\b50x50\b/, `identify "#{@dummy.avatar.path(:thumb)}"`
+      assert_match(/\b50x50\b/, `identify "#{@dummy.avatar.path(:thumb)}"`)
     end
   end
 
diff --git a/test/plural_cache_test.rb b/test/plural_cache_test.rb
index 0e9a1d0..6b67b48 100644
--- a/test/plural_cache_test.rb
+++ b/test/plural_cache_test.rb
@@ -1,6 +1,8 @@
 require 'test_helper'
 
 class PluralCacheTest < Test::Unit::TestCase
+  class BigBox; end
+
   should 'cache pluralizations' do
     cache = Paperclip::Interpolations::PluralCache.new
     symbol = :box
@@ -11,7 +13,6 @@ class PluralCacheTest < Test::Unit::TestCase
   end
 
   should 'cache pluralizations and underscores' do
-    class BigBox ; end
     cache = Paperclip::Interpolations::PluralCache.new
     klass = BigBox
 
@@ -26,7 +27,6 @@ class PluralCacheTest < Test::Unit::TestCase
   end
 
   should 'pluralize and underscore words' do
-    class BigBox ; end
     cache = Paperclip::Interpolations::PluralCache.new
     klass = BigBox
     assert_equal 'plural_cache_test/big_boxes', cache.underscore_and_pluralize_class(klass)
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 984f4fa..3e4684e 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -34,19 +34,19 @@ ActiveRecord::Base.try(:raise_in_transactional_callbacks=, true)
 ActiveRecord::Base.establish_connection(config['test'])
 
 def reset_class class_name
-  ActiveRecord::Base.send(:include, Paperclip)
+  ActiveRecord::Base.include Paperclip
   Object.send(:remove_const, class_name) rescue nil
   klass = Object.const_set(class_name, Class.new(ActiveRecord::Base))
   klass.class_eval{ include Paperclip }
   klass
 end
 
-def reset_table table_name, &block
+def reset_table(_table_name, &block)
   block ||= ->(_) { true }
   ActiveRecord::Base.connection.create_table :dummies, force: true, &block
 end
 
-def modify_table table_name, &block
+def modify_table(_table_name, &block)
   ActiveRecord::Base.connection.change_table :dummies, &block
 end
 
@@ -62,7 +62,7 @@ def rebuild_model options = {}
 end
 
 def rebuild_class(options = {})
-  ActiveRecord::Base.send(:include, Paperclip)
+  ActiveRecord::Base.include Paperclip
   begin
     Object.send(:remove_const, "Dummy")
   rescue StandardError
diff --git a/test/thumbnail_test.rb b/test/thumbnail_test.rb
index 0eb5faf..2feb7a3 100644
--- a/test/thumbnail_test.rb
+++ b/test/thumbnail_test.rb
@@ -73,7 +73,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "create the thumbnail when sent #make" do
         dst = @thumb.make
-        assert_match /100x50/, `identify "#{dst.path}"`
+        assert_match(/100x50/, `identify "#{dst.path}"`)
       end
     end
 
@@ -98,7 +98,7 @@ class ThumbnailTest < Test::Unit::TestCase
 
       should "create the thumbnail when sent #make" do
         dst = @thumb.make
-        assert_match /100x50/, `identify "#{dst.path}"`
+        assert_match(/100x50/, `identify "#{dst.path}"`)
       end
 
       context "redefined to have bad convert_options setting" do