diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..34abf01
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,18 @@
+---
+require: rubocop-rspec
+
+AllCops:
+  TargetRubyVersion: 2.3.7
+
+Layout/ExtraSpacing:
+  AllowForAlignment: false
+
+Metrics/BlockLength:
+  Exclude:
+    - 'spec/**/*_spec.rb'
+
+Metrics/MethodLength:
+  Max: 15
+
+RSpec/NestedGroups:
+  Max: 5
diff --git a/.travis.yml b/.travis.yml
index d64e4ba..217d467 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,6 +12,7 @@ before_install:
   - gem --version
 
 script:
+  - bundle exec rubocop
   - bundle exec rspec
 
 notifications:
diff --git a/Gemfile b/Gemfile
index 851fabc..5f10ba8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 gemspec
diff --git a/bankrupt.gemspec b/bankrupt.gemspec
index 86d6e63..34ef912 100644
--- a/bankrupt.gemspec
+++ b/bankrupt.gemspec
@@ -1,26 +1,31 @@
-lib = File.expand_path("../lib", __FILE__)
+# frozen_string_literal: true
+
+lib = File.expand_path('lib', __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require "bankrupt/version"
+require 'bankrupt/version'
 
 Gem::Specification.new do |spec|
-  spec.name          = "bankrupt"
-  spec.version       = Bankrupt::VERSION
-  spec.authors       = ["Mario Finelli"]
-  spec.email         = ["mario@finel.li"]
+  spec.name = 'bankrupt'
+  spec.version = Bankrupt::VERSION
+  spec.authors = ['Mario Finelli']
+  spec.email = ['mario@finel.li']
 
-  spec.summary       = %q{A sinatra helper to load assets in development and production.}
-  spec.description   = %q{This gem loads files from disk locally and from a CDN in production.}
-  spec.homepage      = "https://github.com/mfinelli/bankrupt"
-  spec.license       = "Apache-2.0"
+  spec.summary = 'A sinatra helper to load assets locally and production.'
+  spec.description = 'Load files from local disk or from a CDN in production.'
+  spec.homepage = 'https://github.com/mfinelli/bankrupt'
+  spec.license = 'Apache-2.0'
+  spec.required_ruby_version = '>= 2.3.0'
 
-  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
+  spec.files = `git ls-files -z`.split("\x0").reject do |f|
     f.match(%r{^(test|spec|features)/})
   end
 
-  spec.require_paths = ["lib"]
+  spec.require_paths = ['lib']
 
   spec.add_dependency 'slim', '~> 3.0'
 
-  spec.add_development_dependency "bundler", "~> 1.16"
-  spec.add_development_dependency "rspec", "~> 3.7"
+  spec.add_development_dependency 'bundler', '~> 1.16'
+  spec.add_development_dependency 'rspec', '~> 3.7'
+  spec.add_development_dependency 'rubocop'
+  spec.add_development_dependency 'rubocop-rspec'
 end
diff --git a/lib/bankrupt.rb b/lib/bankrupt.rb
index 552c2a8..a08bc4e 100644
--- a/lib/bankrupt.rb
+++ b/lib/bankrupt.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+
+# Read assets from a local cache, using files on disk for development and
+# from a CDN url if the CDN constant is set.
 module Bankrupt
   ASSET = Struct.new(:path, :sri).freeze
 
diff --git a/lib/bankrupt/version.rb b/lib/bankrupt/version.rb
index bf65fd8..1b76c25 100644
--- a/lib/bankrupt/version.rb
+++ b/lib/bankrupt/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Bankrupt
   VERSION = '0.1.0'
 end
diff --git a/spec/bankrupt_spec.rb b/spec/bankrupt_spec.rb
index 55be2ab..ef849dd 100644
--- a/spec/bankrupt_spec.rb
+++ b/spec/bankrupt_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'slim'
 require_relative '../lib/bankrupt'
 
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 251aa51..5cac1f5 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,100 +1,20 @@
-# This file was generated by the `rspec --init` command. Conventionally, all
-# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
-# The generated `.rspec` file contains `--require spec_helper` which will cause
-# this file to always be loaded, without a need to explicitly require it in any
-# files.
-#
-# Given that it is always loaded, you are encouraged to keep this file as
-# light-weight as possible. Requiring heavyweight dependencies from this file
-# will add to the boot time of your test suite on EVERY test run, even for an
-# individual file that may not need all of that loaded. Instead, consider making
-# a separate helper file that requires the additional dependencies and performs
-# the additional setup, and require it from the spec files that actually need
-# it.
-#
-# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
+# frozen_string_literal: true
+
 RSpec.configure do |config|
-  # rspec-expectations config goes here. You can use an alternate
-  # assertion/expectation library such as wrong or the stdlib/minitest
-  # assertions if you prefer.
   config.expect_with :rspec do |expectations|
-    # This option will default to `true` in RSpec 4. It makes the `description`
-    # and `failure_message` of custom matchers include text for helper methods
-    # defined using `chain`, e.g.:
-    #     be_bigger_than(2).and_smaller_than(4).description
-    #     # => "be bigger than 2 and smaller than 4"
-    # ...rather than:
-    #     # => "be bigger than 2"
     expectations.include_chain_clauses_in_custom_matcher_descriptions = true
   end
 
-  # rspec-mocks config goes here. You can use an alternate test double
-  # library (such as bogus or mocha) by changing the `mock_with` option here.
   config.mock_with :rspec do |mocks|
-    # Prevents you from mocking or stubbing a method that does not exist on
-    # a real object. This is generally recommended, and will default to
-    # `true` in RSpec 4.
     mocks.verify_partial_doubles = true
   end
 
-  # This option will default to `:apply_to_host_groups` in RSpec 4 (and will
-  # have no way to turn it off -- the option exists only for backwards
-  # compatibility in RSpec 3). It causes shared context metadata to be
-  # inherited by the metadata hash of host groups and examples, rather than
-  # triggering implicit auto-inclusion in groups with matching metadata.
   config.shared_context_metadata_behavior = :apply_to_host_groups
 
-# The settings below are suggested to provide a good initial experience
-# with RSpec, but feel free to customize to your heart's content.
-=begin
-  # This allows you to limit a spec run to individual examples or groups
-  # you care about by tagging them with `:focus` metadata. When nothing
-  # is tagged with `:focus`, all examples get run. RSpec also provides
-  # aliases for `it`, `describe`, and `context` that include `:focus`
-  # metadata: `fit`, `fdescribe` and `fcontext`, respectively.
-  config.filter_run_when_matching :focus
-
-  # Allows RSpec to persist some state between runs in order to support
-  # the `--only-failures` and `--next-failure` CLI options. We recommend
-  # you configure your source control system to ignore this file.
-  config.example_status_persistence_file_path = "spec/examples.txt"
-
-  # Limits the available syntax to the non-monkey patched syntax that is
-  # recommended. For more details, see:
-  #   - http://rspec.info/blog/2012/06/rspecs-new-expectation-syntax/
-  #   - http://www.teaisaweso.me/blog/2013/05/27/rspecs-new-message-expectation-syntax/
-  #   - http://rspec.info/blog/2014/05/notable-changes-in-rspec-3/#zero-monkey-patching-mode
   config.disable_monkey_patching!
+  config.default_formatter = 'doc' if config.files_to_run.one?
 
-  # This setting enables warnings. It's recommended, but in some cases may
-  # be too noisy due to issues in dependencies.
-  config.warnings = true
-
-  # Many RSpec users commonly either run the entire suite or an individual
-  # file, and it's useful to allow more verbose output when running an
-  # individual spec file.
-  if config.files_to_run.one?
-    # Use the documentation formatter for detailed output,
-    # unless a formatter has already been configured
-    # (e.g. via a command-line flag).
-    config.default_formatter = "doc"
-  end
-
-  # Print the 10 slowest examples and example groups at the
-  # end of the spec run, to help surface which specs are running
-  # particularly slow.
   config.profile_examples = 10
-
-  # Run specs in random order to surface order dependencies. If you find an
-  # order dependency and want to debug it, you can fix the order by providing
-  # the seed, which is printed after each run.
-  #     --seed 1234
   config.order = :random
-
-  # Seed global randomization in this process using the `--seed` CLI option.
-  # Setting this allows you to use `--seed` to deterministically reproduce
-  # test failures related to randomization by passing the same `--seed` value
-  # as the one that triggered the failure.
   Kernel.srand config.seed
-=end
 end