diff --git a/.rubocop.yml b/.rubocop.yml
index c713137..6aa13d1 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -5,6 +5,9 @@ AllCops:
   Exclude:
     - lib/one_gadget/builds/*.rb
 
+Gemspec/RequireMFA:
+  Enabled: false
+
 Gemspec/RequiredRubyVersion:
   Enabled: false
 
@@ -18,6 +21,12 @@ Layout/LineLength:
   Enabled: true
   Max: 120
 
+Lint/AmbiguousOperatorPrecedence:
+  Enabled: false
+
+Lint/AmbiguousRange:
+  Enabled: false
+
 Metrics/AbcSize:
   Enabled: false
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 31c3c53..5e62f7a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -10,16 +10,16 @@ GEM
     ast (2.4.2)
     bindata (2.4.10)
     diff-lcs (1.5.0)
-    docile (1.3.5)
+    docile (1.4.0)
     elftools (1.1.3)
       bindata (~> 2)
-    json (2.5.1)
-    parallel (1.20.1)
-    parser (3.0.0.0)
+    json (2.6.1)
+    parallel (1.21.0)
+    parser (3.1.1.0)
       ast (~> 2.4.1)
-    rainbow (3.0.0)
+    rainbow (3.1.1)
     rake (13.0.6)
-    regexp_parser (2.1.1)
+    regexp_parser (2.2.1)
     rexml (3.2.5)
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
@@ -34,24 +34,24 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    rubocop (1.12.1)
+    rubocop (1.26.0)
       parallel (~> 1.10)
-      parser (>= 3.0.0.0)
+      parser (>= 3.1.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
       rexml
-      rubocop-ast (>= 1.2.0, < 2.0)
+      rubocop-ast (>= 1.16.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.4.1)
-      parser (>= 2.7.1.5)
+    rubocop-ast (1.16.0)
+      parser (>= 3.1.1.0)
     ruby-progressbar (1.11.0)
     simplecov (0.17.1)
       docile (~> 1.1)
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    unicode-display_width (2.0.0)
+    unicode-display_width (2.1.0)
     webrick (1.7.0)
     yard (0.9.27)
       webrick (~> 1.7.0)
diff --git a/lib/one_gadget/cli.rb b/lib/one_gadget/cli.rb
index c097573..030ed6a 100644
--- a/lib/one_gadget/cli.rb
+++ b/lib/one_gadget/cli.rb
@@ -120,7 +120,7 @@ module OneGadget
         end
 
         opts.on('-n', '--near FUNCTIONS/FILE', 'Order gadgets by their distance to the given functions'\
-                ' or to the GOT functions of the given file.') do |n|
+                                               ' or to the GOT functions of the given file.') do |n|
           @options[:near] = n
         end
 
diff --git a/lib/one_gadget/fetchers/base.rb b/lib/one_gadget/fetchers/base.rb
index bff5a85..9c65f44 100644
--- a/lib/one_gadget/fetchers/base.rb
+++ b/lib/one_gadget/fetchers/base.rb
@@ -192,7 +192,7 @@ module OneGadget
       end
 
       def str_offset(str)
-        IO.binread(file).index("#{str}\x00") ||
+        File.binread(file).index("#{str}\x00") ||
           raise(Error::ArgumentError, "File #{file.inspect} doesn't contain string #{str.inspect}, not glibc?")
       end
 
diff --git a/lib/one_gadget/update.rb b/lib/one_gadget/update.rb
index b2b68da..8206a31 100644
--- a/lib/one_gadget/update.rb
+++ b/lib/one_gadget/update.rb
@@ -42,7 +42,7 @@ module OneGadget
         # don't check if not CLI
         return false unless $stdout.tty?
         return false if cache.nil? # cache file fails, no update check.
-        return false if IO.binread(cache).strip == 'never'
+        return false if File.binread(cache).strip == 'never'
 
         Time.now >= last_check + FREQUENCY
       end
@@ -57,7 +57,7 @@ module OneGadget
       def cache_file
         dir = File.dirname(CACHE_FILE)
         FileUtils.mkdir_p(dir) unless File.directory?(dir)
-        IO.binwrite(CACHE_FILE, '') unless File.exist?(CACHE_FILE)
+        File.binwrite(CACHE_FILE, '') unless File.exist?(CACHE_FILE)
         CACHE_FILE
       rescue Errno::EACCES # prevent dir is not writable
         nil
diff --git a/spec/update_spec.rb b/spec/update_spec.rb
index 82e779a..d38abb9 100644
--- a/spec/update_spec.rb
+++ b/spec/update_spec.rb
@@ -40,7 +40,7 @@ describe OneGadget::Update do
       allow(Time).to receive(:now).and_return(now + 30 * 24 * 3600)
       allow($stdout).to receive(:tty?).and_return(true)
       expect(described_class.__send__(:need_check?)).to be true
-      IO.binwrite(path, 'never')
+      File.binwrite(path, 'never')
       expect(described_class.__send__(:need_check?)).to be false
     end
   end
diff --git a/tasks/builds/generate.rake b/tasks/builds/generate.rake
index 8d77820..fd4a65c 100644
--- a/tasks/builds/generate.rake
+++ b/tasks/builds/generate.rake
@@ -47,11 +47,11 @@ namespace :builds do
       next failed('no gadgets found') if gadgets.empty?
 
       content = template(info, gadgets)
-      File.open(filename, 'w') { |f| f.write(content) }
+      File.write(filename, content)
       puts 'done'
     end
     puts "Total #{total} files, \e[32m#{total - @skipped - @failed}\e[0m succeeded, " \
-      "\e[33m#{@skipped}\e[0m skipped, and \e[31m#{@failed}\e[0m failed."
+         "\e[33m#{@skipped}\e[0m skipped, and \e[31m#{@failed}\e[0m failed."
   end
 
   def template(info, gadgets)
diff --git a/tasks/readme.rake b/tasks/readme.rake
index 7d59a22..5b9b612 100644
--- a/tasks/readme.rake
+++ b/tasks/readme.rake
@@ -4,7 +4,7 @@ desc 'To auto generate README.md from README.tpl'
 task :readme do
   next if ENV['CI']
 
-  @tpl = IO.binread('README.tpl.md')
+  @tpl = File.binread('README.tpl.md')
 
   def replace(prefix)
     @tpl.gsub!(/#{prefix}\(.*\)/) do |s|
@@ -27,5 +27,5 @@ task :readme do
     "#{cmd}\n#=> #{res.inspect}\n"
   end
 
-  IO.binwrite('README.md', @tpl)
+  File.binwrite('README.md', @tpl)
 end