diff --git a/.rubocop.yml b/.rubocop.yml
index 9e2b76b..6e2ceb7 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,4 +1,5 @@
 inherit_from: .rubocop_todo.yml
+require: rubocop-rspec
 
 AllCops:
   NewCops: enable
diff --git a/heartcheck.gemspec b/heartcheck.gemspec
index cf9adea..99a0814 100644
--- a/heartcheck.gemspec
+++ b/heartcheck.gemspec
@@ -14,6 +14,8 @@ Gem::Specification.new do |spec|
   spec.description = 'A simple way to check your app heart.'
   spec.license = 'MIT'
 
+  spec.metadata['rubygems_mfa_required'] = 'true'
+
   spec.files = `git ls-files -z`.split("\x0").reject do |f|
     f.match(%r{^(test|spec|features)/})
   end
@@ -35,6 +37,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'rspec', '~> 3.5.0'
   spec.add_development_dependency 'rubocop'
+  spec.add_development_dependency 'rubocop-rspec'
   spec.add_development_dependency 'rubycritic'
   spec.add_development_dependency 'thor', '~> 0.19.1'
   spec.add_development_dependency 'yard', '~> 0.9.5'
diff --git a/spec/lib/heartcheck/app_spec.rb b/spec/lib/heartcheck/app_spec.rb
index eeaf799..7fb952e 100644
--- a/spec/lib/heartcheck/app_spec.rb
+++ b/spec/lib/heartcheck/app_spec.rb
@@ -6,9 +6,10 @@
 describe Heartcheck::App do
   include Rack::Test::Methods
 
-  let(:app) { described_class.new }
   subject   { last_response }
 
+  let(:app) { described_class.new }
+
   describe '#body' do
     subject { super().body }
 
@@ -25,21 +26,23 @@
     it { is_expected.to eq(200) }
   end
 
-  context 'on GET /functional' do
+  context 'with GET /functional' do
     before { get '/functional' }
 
     describe '#body' do
       subject { super().body }
+
       it { is_expected.to eq('[]') }
     end
 
     describe '#status' do
       subject { super().status }
+
       it { is_expected.to eq(200) }
     end
   end
 
-  context 'on GET /dev' do
+  context 'with GET /dev' do
     before do
       Heartcheck.setup do |monitor|
         log = Logger.new($stdout)
@@ -55,54 +58,62 @@
     it 'has execution_time' do
       expect(subject.body).to match(/"execution_time":"([0-9]{1,2}).([0-9]{2}) ms"/)
     end
+
     it 'has total_execution_time' do
       expect(subject.body).to match(/"total_execution_time":"([0-9]{1,2}).([0-9]{2}) ms"/)
     end
 
     describe '#status' do
       subject { super().status }
+
       it { is_expected.to eq(200) }
     end
   end
 
-  context 'on GET info' do
+  context 'with GET info' do
     before { get '/info' }
 
     describe '#body' do
       subject { super().body }
+
       it { is_expected.to eq('[]') }
     end
 
     describe '#status' do
       subject { super().status }
+
       it { is_expected.to eq(200) }
     end
   end
 
-  context 'on GET health_check' do
+  context 'with GET health_check' do
     before { get '/health_check' }
 
     describe '#body' do
       subject { super().body }
+
       it { is_expected.to eq(MultiJson.dump({ status: 'ok' })) }
     end
 
     describe '#status' do
       subject { super().status }
+
       it { is_expected.to eq(200) }
     end
   end
 
-  context 'on GET other routes' do
+  context 'with GET other routes' do
     before { get '/lorem' }
 
     describe '#body' do
       subject { super().body }
+
       it { is_expected.to eq('Not found') }
     end
 
     describe '#status' do
       subject { super().status }
+
       it { is_expected.to eq(404) }
     end
   end
diff --git a/spec/lib/heartcheck/caching_app_spec.rb b/spec/lib/heartcheck/caching_app_spec.rb
index 89f4942..54e8c58 100644
--- a/spec/lib/heartcheck/caching_app_spec.rb
+++ b/spec/lib/heartcheck/caching_app_spec.rb
@@ -9,8 +9,8 @@ module Heartcheck
 
     let(:app) { described_class.new(super_app, ttl, cache) }
     let(:ttl) { 5 }
-    let(:cache) { double(Heartcheck::CachingApp::Cache) }
-    let(:super_app) { double(Heartcheck::App) }
+    let(:cache) { instance_double(Heartcheck::CachingApp::Cache) }
+    let(:super_app) { instance_double(Heartcheck::App) }
     let(:controller) { Heartcheck::Controllers::Essential }
     let(:response) { [200, { 'Content-type' => 'application/json' }, ['[]']] }
 
@@ -61,7 +61,7 @@ module Heartcheck
       end
     end
 
-    context 'on an unknown route' do
+    context 'with an unknown route' do
       it 'forwards to the original app' do
         get '/not-found'
 
diff --git a/spec/lib/heartcheck/checks/base_spec.rb b/spec/lib/heartcheck/checks/base_spec.rb
index 841ad0f..d8f28fc 100644
--- a/spec/lib/heartcheck/checks/base_spec.rb
+++ b/spec/lib/heartcheck/checks/base_spec.rb
@@ -80,36 +80,40 @@
   end
 
   describe '#functional?' do
-    context 'default is false' do
+    context 'when functional is not set' do
       describe '#functional?' do
         subject { super().functional? }
+
         it { is_expected.to be_falsey }
       end
     end
 
-    context 'can change value' do
+    context 'when functional is set to true' do
       before { base.functional = true }
 
       describe '#functional?' do
         subject { super().functional? }
+
         it { is_expected.to be_truthy }
       end
     end
   end
 
   describe '#dev?' do
-    context 'default is false' do
+    context 'when dev is not set' do
       describe '#dev?' do
         subject { super().dev? }
+
         it { is_expected.to be_falsey }
       end
     end
 
-    context 'can change value' do
+    context 'when dev is set to true' do
       before { base.dev = true }
 
       describe '#dev?' do
         subject { super().dev? }
+
         it { is_expected.to be_truthy }
       end
     end
@@ -120,6 +124,7 @@
 
     context 'with success' do
       before { allow(subject).to receive(:validate) }
+
       it 'returns empty array' do
         expect(subject.check).to eq('base' => { 'status' => 'ok' })
       end
@@ -143,7 +148,7 @@
         )
       end
 
-      it 'should not accumulate errors' do
+      it 'does not accumulate errors' do
         subject.check
         expect(subject.check).to eq(
           'base' => {
@@ -195,24 +200,23 @@
 
     context 'without error' do
       let(:response) { { 'version' => '1234' } }
+
       before do
         allow(subject).to receive(:info).and_return(response)
       end
 
-      it 'should show a response' do
+      it 'shows a response' do
         expect(subject.informations).to eq(response)
       end
     end
   end
 
   describe '#uri_info' do
-    context 'for the base class' do
-      it 'returns a hash with an error message' do
-        expect(subject.uri_info).to include(:error)
-        expect(subject.uri_info).not_to include(:host)
-        expect(subject.uri_info).not_to include(:port)
-        expect(subject.uri_info).not_to include(:schema)
-      end
+    it 'returns a hash with an error message' do
+      expect(subject.uri_info).to include(:error)
+      expect(subject.uri_info).not_to include(:host)
+      expect(subject.uri_info).not_to include(:port)
+      expect(subject.uri_info).not_to include(:schema)
     end
   end
 end
diff --git a/spec/lib/heartcheck/checks/firewall_spec.rb b/spec/lib/heartcheck/checks/firewall_spec.rb
index 9fbe76d..b75f1b6 100644
--- a/spec/lib/heartcheck/checks/firewall_spec.rb
+++ b/spec/lib/heartcheck/checks/firewall_spec.rb
@@ -40,7 +40,7 @@
 
     context 'without proxy' do
       context 'with success' do
-        let(:telnet) { double(Net::Telnet, close: true) }
+        let(:telnet) { instance_double(Net::Telnet, close: true) }
         let(:params) { { 'Port' => 443, 'Host' => 'lala.com', 'Timeout' => 2 } }
 
         it 'calls Net::Telnet with valid params' do
@@ -50,7 +50,7 @@
         end
       end
 
-      context 'with success' do
+      context 'without success' do
         before { allow(Net::Telnet).to receive(:new).and_raise(Timeout::Error.new) }
 
         it 'adds error message' do
@@ -72,16 +72,16 @@
     end
 
     context 'with proxy' do
-      let(:host) { 'lala.com' }
-      let(:port) { 443 }
-      let(:proxy) { 'http://uriproxy.com.br:8888' }
-
       subject do
         described_class.new.tap do |c|
           c.add_service(port: port, host: host, proxy: proxy)
         end
       end
 
+      let(:host) { 'lala.com' }
+      let(:port) { 443 }
+      let(:proxy) { 'http://uriproxy.com.br:8888' }
+
       it 'calls Net::Telnet with valid params of proxy' do
         expect(Net::Telnet).to receive(:new).with('Port' => 8888, 'Host' => 'uriproxy.com.br',
                                                   'Timeout' => 2).ordered.and_return('proxy')
@@ -91,7 +91,7 @@
         subject.validate
       end
 
-      context 'connection refused' do
+      context 'when getting connection is refused' do
         it 'avoid to adds errors array' do
           expect(Net::Telnet).to receive(:new).and_raise Errno::ECONNREFUSED.new
           subject.validate
@@ -100,7 +100,7 @@
         end
       end
 
-      context 'timeout' do
+      context 'when running into a timeout' do
         let(:proxy_uri) { 'uriproxy.com.br:8888' }
         let(:error_msg) do
           "connection refused on: #{host}:443 using proxy: #{proxy_uri}"
diff --git a/spec/lib/heartcheck/checks/process_spec.rb b/spec/lib/heartcheck/checks/process_spec.rb
index e5fb7d2..5263c87 100644
--- a/spec/lib/heartcheck/checks/process_spec.rb
+++ b/spec/lib/heartcheck/checks/process_spec.rb
@@ -3,9 +3,10 @@
 require 'spec_helper'
 
 describe Heartcheck::Checks::Process do
-  let(:opts) { { name: 'worker', file: 'spec/fixtures/files/worker.pid' } }
   subject    { described_class.new.tap { |c| c.add_service(opts) } }
 
+  let(:opts) { { name: 'worker', file: 'spec/fixtures/files/worker.pid' } }
+
   describe '#validate' do
     context 'with success' do
       it 'calls process kill 0' do
diff --git a/spec/lib/heartcheck/checks/watch_file_spec.rb b/spec/lib/heartcheck/checks/watch_file_spec.rb
index 9209e22..67bbb44 100644
--- a/spec/lib/heartcheck/checks/watch_file_spec.rb
+++ b/spec/lib/heartcheck/checks/watch_file_spec.rb
@@ -8,14 +8,14 @@
   end
 
   describe '#validate' do
-    context 'the watched file as no modifications' do
+    context 'when the watched file as no modifications' do
       it 'array errors should be empty' do
         subject.validate
         expect(subject.instance_variable_get(:@errors)).to be_empty
       end
     end
 
-    context 'the watched file have new modifications' do
+    context 'when the watched file have new modifications' do
       it 'array erros should not be empty' do
         allow(subject).to receive(:installed).and_return({ bacon: true })
         expect { subject.validate }
diff --git a/spec/lib/heartcheck/controllers/environment_spec.rb b/spec/lib/heartcheck/controllers/environment_spec.rb
index 9837a51..4a7a5ae 100644
--- a/spec/lib/heartcheck/controllers/environment_spec.rb
+++ b/spec/lib/heartcheck/controllers/environment_spec.rb
@@ -13,14 +13,24 @@ module Controllers
 
         let(:system_info_example) { Struct.new(:example_key).new('example_value') }
 
-        context 'given Rails is used' do
+        context 'when Rails is used' do
           before do
             stub_const('Rails::VERSION::STRING', '5.0.0')
           end
 
+          let(:rails_version) do
+            MultiJson.load(controller.index, symbolize_keys: true)[:rails_version]
+          end
+          let(:ruby_version) do
+            MultiJson.load(controller.index, symbolize_keys: true)[:ruby_version]
+          end
+          let(:system_info) do
+            MultiJson.load(controller.index, symbolize_keys: true)[:system_info]
+          end
+
           it 'gets info from the right constants and functions' do
             allow(Sys::Uname).to receive(:uname).and_return(system_info_example)
-            is_expected.to include(
+            expect(subject).to include(
               system_info: { example_key: 'example_value' },
               ruby_version: '2.4.0',
               rails_version: '5.0.0'
@@ -28,18 +38,6 @@ module Controllers
             expect(Sys::Uname).to have_received(:uname)
           end
 
-          let(:system_info) do
-            MultiJson.load(controller.index, symbolize_keys: true)[:system_info]
-          end
-
-          let(:ruby_version) do
-            MultiJson.load(controller.index, symbolize_keys: true)[:ruby_version]
-          end
-
-          let(:rails_version) do
-            MultiJson.load(controller.index, symbolize_keys: true)[:rails_version]
-          end
-
           it 'gets the info in the expected format' do
             expect(system_info).to be_a(Hash)
             expect(system_info).to include(
@@ -61,10 +59,10 @@ module Controllers
           end
         end
 
-        context 'given Rails is not used' do
+        context 'when Rails is not used' do
           it 'gets the info indicating Rails is not used' do
             allow(Sys::Uname).to receive(:uname).and_return(system_info_example)
-            is_expected.to include(
+            expect(subject).to include(
               system_info: { example_key: 'example_value' },
               ruby_version: '2.4.0',
               rails_version: '(none)'
diff --git a/spec/lib/heartcheck/executors/base_spec.rb b/spec/lib/heartcheck/executors/base_spec.rb
index 4149dbf..12883b5 100644
--- a/spec/lib/heartcheck/executors/base_spec.rb
+++ b/spec/lib/heartcheck/executors/base_spec.rb
@@ -16,18 +16,16 @@ module Executors
           end
         end
 
-        it 'should register a log entry for each checker' do
+        it 'registers a log entry for each checker' do
           expect(Logger).to receive(:info).exactly(registered).times
           subject.dispatch(checkers)
         end
 
-        it 'should have a :time key in the checker response' do
-          subject.dispatch(checkers).each do |current|
-            expect(current).to include(:time)
-          end
+        it 'has a :time key in the checker response' do
+          expect(subject.dispatch(checkers)).to all(include(:time))
         end
 
-        it 'should have a float value (time key)' do
+        it 'has a float value (time key)' do
           subject.dispatch(checkers).each do |current|
             expect(current[:time]).to be_a(Float)
           end
diff --git a/spec/lib/heartcheck/executors/threaded_spec.rb b/spec/lib/heartcheck/executors/threaded_spec.rb
index ac54ccd..6bad0b4 100644
--- a/spec/lib/heartcheck/executors/threaded_spec.rb
+++ b/spec/lib/heartcheck/executors/threaded_spec.rb
@@ -22,18 +22,16 @@ module Executors
           end
         end
 
-        it 'should register a log entry for each checker' do
+        it 'registers a log entry for each checker' do
           expect(Logger).to receive(:info).exactly(registered).times
           subject.dispatch(checkers)
         end
 
-        it 'should have a :time key in the checker response' do
-          subject.dispatch(checkers).each do |current|
-            expect(current).to include(:time)
-          end
+        it 'has a :time key in the checker response' do
+          expect(subject.dispatch(checkers)).to all(include(:time))
         end
 
-        it 'should have a float value (time key)' do
+        it 'has a float value (time key)' do
           subject.dispatch(checkers).each do |current|
             expect(current[:time]).to be_a(Float)
           end
diff --git a/spec/lib/heartcheck_spec.rb b/spec/lib/heartcheck_spec.rb
index 0328abf..43230e9 100644
--- a/spec/lib/heartcheck_spec.rb
+++ b/spec/lib/heartcheck_spec.rb
@@ -25,7 +25,8 @@
 
   describe '#format' do
     context 'with default' do
-      before(:each) { described_class.instance_variable_set :@formatter, nil }
+      before { described_class.instance_variable_set :@formatter, nil }
+
       it 'returns a Heartcheck::Formatters::Base' do
         described_class.setup do |monitor|
           expect(monitor.formatter).to be_a(Heartcheck::Formatters::Base)
@@ -34,7 +35,8 @@
     end
 
     context 'with hash formatter' do
-      before(:each) { described_class.instance_variable_set :@formatter, nil }
+      before { described_class.instance_variable_set :@formatter, nil }
+
       it 'returns a Heartcheck::Formatters::Base' do
         described_class.setup do |monitor|
           described_class.use_hash_formatter!
@@ -61,7 +63,7 @@
     end
 
     context 'with threaded' do
-      it 'returns a threaded  executor' do
+      it 'returns a threaded executor' do
         described_class.use_threaded_executor!
         expect(described_class.executor).to be_a(Heartcheck::Executors::Threaded)
       end
@@ -96,9 +98,8 @@
     subject(:add) { described_class.add(name, &blk) }
 
     let(:name) { :process }
-    let(:plugin) { Heartcheck::Checks::Process.new }
-
     let(:blk) { ->(_) {} }
+    let(:plugin) { Heartcheck::Checks::Process.new }
 
     before do
       allow(Heartcheck::Checks::Process).to receive(:new)
@@ -107,7 +108,7 @@
     end
 
     it 'returns the built instance' do
-      is_expected.to eq([plugin])
+      expect(subject).to eq([plugin])
     end
 
     it 'adds to context list' do
@@ -118,12 +119,14 @@
       )
     end
 
-    let(:blk) { ->(c) { c.this_is_terrible } }
+    context 'with code in the block argument' do
+      let(:blk) { ->(c) { c.this_is_terrible } }
 
-    it 'instantiates the class passing the given block' do
-      expect(plugin).to receive(:this_is_terrible)
+      it 'instantiates the class passing the given block' do
+        expect(plugin).to receive(:this_is_terrible)
 
-      add
+        add
+      end
     end
   end
 end