diff --git a/.rubocop.yml b/.rubocop.yml
index 660803d..8c73e93 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,7 +1,7 @@
 inherit_from: .rubocop_todo.yml
 
 AllCops:
-  TargetRubyVersion: 2.4
+  TargetRubyVersion: 2.6
   NewCops: enable
 
 Layout/LineLength:
diff --git a/devbox.json b/devbox.json
index 4fbb86c..1be2d41 100644
--- a/devbox.json
+++ b/devbox.json
@@ -3,7 +3,8 @@
   "packages": ["ruby@2.6.8"],
   "shell": {
     "scripts": {
-      "test": ["bundle exec rspec $@"]
+      "test": ["bundle exec rspec $@"],
+      "lint": ["bundle exec rubocop -a $@"]
     }
   }
 }
diff --git a/lib/vero/api/users/delete_api.rb b/lib/vero/api/users/delete_api.rb
index 275031b..d13f106 100644
--- a/lib/vero/api/users/delete_api.rb
+++ b/lib/vero/api/users/delete_api.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Vero
   module Api
     module Workers
@@ -12,7 +14,7 @@ def request
           end
 
           def validate!
-            raise ArgumentError.new("Missing :id") if options[:id].to_s.blank?
+            raise ArgumentError, 'Missing :id' if options[:id].to_s.blank?
           end
         end
       end
diff --git a/lib/vero/config.rb b/lib/vero/config.rb
index e41c20e..219cb3b 100644
--- a/lib/vero/config.rb
+++ b/lib/vero/config.rb
@@ -23,7 +23,7 @@ def request_params
       {
         auth_token: auth_token,
         development_mode: development_mode
-      }.reject { |_, v| v.nil? }
+      }.compact
     end
 
     def domain
diff --git a/spec/lib/api/users/delete_api_spec.rb b/spec/lib/api/users/delete_api_spec.rb
index 0c1dd9a..5170996 100644
--- a/spec/lib/api/users/delete_api_spec.rb
+++ b/spec/lib/api/users/delete_api_spec.rb
@@ -1,31 +1,33 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Vero::Api::Workers::Users::DeleteAPI do
-  subject { Vero::Api::Workers::Users::DeleteAPI.new('https://api.getvero.com', {:auth_token => 'abcd', :id => '1234'}) }
+  subject { Vero::Api::Workers::Users::DeleteAPI.new('https://api.getvero.com', { auth_token: 'abcd', id: '1234' }) }
 
-  it_behaves_like "a Vero wrapper" do
-    let(:end_point) { "/api/v2/users/delete.json" }
+  it_behaves_like 'a Vero wrapper' do
+    let(:end_point) { '/api/v2/users/delete.json' }
   end
 
-  it_behaves_like "a Vero wrapper" do
-    let(:end_point) { "/api/v2/users/delete.json" }
+  it_behaves_like 'a Vero wrapper' do
+    let(:end_point) { '/api/v2/users/delete.json' }
   end
 
   describe :validate! do
-    it "should not raise an error when the keys are Strings" do
-      subject.options = {"auth_token" => 'abcd', "id" => '1234'}
+    it 'should not raise an error when the keys are Strings' do
+      subject.options = { 'auth_token' => 'abcd', 'id' => '1234' }
       expect { subject.send(:validate!) }.to_not raise_error
     end
 
-    it "should raise an error for missing keys" do
-      subject.options = {"auth_token" => 'abcd'}
+    it 'should raise an error for missing keys' do
+      subject.options = { 'auth_token' => 'abcd' }
       expect { subject.send(:validate!) }.to raise_error(ArgumentError)
     end
   end
 
   describe :request do
-    it "should send a request to the Vero API" do
-      expect(RestClient).to receive(:post).with("https://api.getvero.com/api/v2/users/delete.json", {:auth_token => 'abcd', :id => '1234'}).and_return(200)
+    it 'should send a request to the Vero API' do
+      expect(RestClient).to receive(:post).with('https://api.getvero.com/api/v2/users/delete.json', { auth_token: 'abcd', id: '1234' }).and_return(200)
       subject.send(:request)
     end
   end
diff --git a/spec/lib/app_spec.rb b/spec/lib/app_spec.rb
index 9ab00e1..6985be7 100644
--- a/spec/lib/app_spec.rb
+++ b/spec/lib/app_spec.rb
@@ -42,7 +42,7 @@
 
   describe :disable_requests! do
     it 'should change config.disabled' do
-      Vero::App.init {}
+      Vero::App.init
       expect(context.config.disabled).to be(false)
 
       Vero::App.disable_requests!
@@ -52,7 +52,7 @@
 
   describe :log do
     it 'should have a log method' do
-      Vero::App.init {}
+      Vero::App.init
       expect(Vero::App).to receive(:log)
       Vero::App.log(Object, 'test')
     end
diff --git a/spec/lib/view_helpers_spec.rb b/spec/lib/view_helpers_spec.rb
index fe6f317..cba4c78 100644
--- a/spec/lib/view_helpers_spec.rb
+++ b/spec/lib/view_helpers_spec.rb
@@ -23,7 +23,7 @@
     it 'should return an empty string if Vero::App is not properly configured' do
       expect(subject.vero_javascript_tag).to eq('')
 
-      Vero::App.init {}
+      Vero::App.init
       expect(subject.vero_javascript_tag).to eq('')
     end
 
diff --git a/spec/support/vero_user_support.rb b/spec/support/vero_user_support.rb
index 5cfd6b1..146490c 100644
--- a/spec/support/vero_user_support.rb
+++ b/spec/support/vero_user_support.rb
@@ -1,4 +1,3 @@
 # frozen_string_literal: true
 
-VeroUser = Struct.new(:api_key, :secret) do
-end
+VeroUser = Struct.new(:api_key, :secret)
diff --git a/vero.gemspec b/vero.gemspec
index bb75903..9a96e78 100644
--- a/vero.gemspec
+++ b/vero.gemspec
@@ -6,7 +6,6 @@ require 'vero/version'
 Gem::Specification.new do |spec|
   spec.name     = 'vero'
   spec.version  = Vero::VERSION.dup
-  spec.date     = Time.now.strftime('%Y-%m-%d')
   spec.authors  = ['James Lamont']
   spec.email    = ['support@getvero.com']
 
@@ -15,7 +14,6 @@ Gem::Specification.new do |spec|
   spec.homepage = 'http://www.getvero.com/'
 
   spec.files         = Dir['**/*']
-  spec.test_files    = Dir['test/**/*'] + Dir['spec/**/*']
   spec.executables   = Dir['bin/*'].map { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
@@ -23,4 +21,5 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency 'json'
   spec.add_runtime_dependency 'rest-client'
+  spec.metadata['rubygems_mfa_required'] = 'true'
 end