diff --git a/.rubocop.yml b/.rubocop.yml
index 35f4bd7567..244fe8442d 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,5 +1,5 @@
 AllCops:
-  TargetRubyVersion: 2.0
+  TargetRubyVersion: 2.5
   DisplayCopNames: true
   Exclude:
     - "tasks/**/*"
diff --git a/Gemfile b/Gemfile
index 19ecc488a5..f3f7c48f4a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,18 +8,15 @@ gem 'rake'
 
 gem 'minitest', '>= 5.0'
 gem 'minitest-power_assert'
-gem 'power_assert', '~> 1.2'
+gem 'power_assert', '~> 2.0.1'
 
-gem 'parallel', '~> 1.13.0' if RUBY_VERSION < '2.2.0'
 gem 'rubocop', '~> 0.49.1'
 
 # don't try to install redcarpet under jruby
-gem 'redcarpet', :platforms => :ruby
+gem 'redcarpet', platforms: :ruby
 
 # Profiling
-if RUBY_VERSION >= '2.3.0'
-  gem 'memory_profiler', :require => false
-end
+gem 'memory_profiler', require: false
 
 # Needed for a Rake task
 gem 'git'
@@ -32,11 +29,7 @@ group :development do
   gem 'github-markup'
 
   # for visual tests
-  if RUBY_VERSION < '2.2.0'
-    gem 'sinatra', '~> 1.4.8'
-  else
-    gem 'sinatra'
-  end
+  gem 'sinatra'
 
   # Ruby 3 no longer ships with a web server
   gem 'puma' if RUBY_VERSION >= '3'
diff --git a/rouge.gemspec b/rouge.gemspec
index c03687639c..a041b428d8 100644
--- a/rouge.gemspec
+++ b/rouge.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.files = Dir['Gemfile', 'LICENSE', 'rouge.gemspec', 'lib/**/*.rb', 'lib/**/*.yml', 'bin/rougify', 'lib/rouge/demos/*']
   s.executables = %w(rougify)
   s.licenses = ['MIT', 'BSD-2-Clause']
-  s.required_ruby_version = '>= 2.0'
+  s.required_ruby_version = '>= 2.5'
   s.metadata = {
     "bug_tracker_uri"   => "https://github.com/rouge-ruby/rouge/issues",
     "changelog_uri"     => "https://github.com/rouge-ruby/rouge/blob/master/CHANGELOG.md",