diff --git a/.github/workflows/specs.yml b/.github/workflows/specs.yml
index 470a629..a8be957 100644
--- a/.github/workflows/specs.yml
+++ b/.github/workflows/specs.yml
@@ -13,7 +13,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: ['2.6', '2.7', '3.0']
+        ruby: ['2.5', '2.6', '2.7', '3.0']
 
     steps:
       - name: Checkout repository
diff --git a/.rubocop.yml b/.rubocop.yml
index 2edf5b3..64b4698 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -34,3 +34,12 @@ RSpec/ExampleLength:
 RSpec/MultipleMemoizedHelpers:
   # default: 5
   Max: 6
+
+RSpec/SubjectStub:
+  Exclude:
+    - spec/units/prawn_html/attributes_spec.rb
+
+Style/OpenStructUse:
+  Exclude:
+    - lib/prawn_html/attributes.rb
+    - spec/units/prawn_html/attributes_spec.rb
diff --git a/prawn-html.gemspec b/prawn-html.gemspec
index 690653e..954d174 100644
--- a/prawn-html.gemspec
+++ b/prawn-html.gemspec
@@ -9,12 +9,17 @@ Gem::Specification.new do |spec|
   spec.version       = PrawnHtml::VERSION
   spec.summary       = 'Prawn PDF - HTML renderer'
   spec.description   = 'HTML to PDF with Prawn PDF'
+
   spec.required_ruby_version = '>= 2.5.0'
 
-  spec.license       = 'MIT'
-  spec.authors       = ['Mattia Roccoberton']
-  spec.email         = 'mat@blocknot.es'
-  spec.homepage      = 'https://github.com/blocknotes/prawn-html'
+  spec.license  = 'MIT'
+  spec.authors  = ['Mattia Roccoberton']
+  spec.email    = 'mat@blocknot.es'
+  spec.homepage = 'https://github.com/blocknotes/prawn-html'
+
+  spec.metadata['homepage_uri']          = spec.homepage
+  spec.metadata['source_code_uri']       = spec.homepage
+  spec.metadata['rubygems_mfa_required'] = 'true'
 
   spec.files         = Dir['lib/**/*', 'LICENSE.txt', 'README.md']
   spec.require_paths = ['lib']
diff --git a/spec/units/prawn_html/utils_spec.rb b/spec/units/prawn_html/utils_spec.rb
index 485ce09..b925d83 100644
--- a/spec/units/prawn_html/utils_spec.rb
+++ b/spec/units/prawn_html/utils_spec.rb
@@ -127,13 +127,13 @@
     context 'with a nil value' do
       let(:value) { nil }
 
-      it { is_expected.to eq nil }
+      it { is_expected.to be_nil }
     end
 
     context 'with a blank string value' do
       let(:value) { '' }
 
-      it { is_expected.to eq nil }
+      it { is_expected.to be_nil }
     end
 
     context 'with a string value (ex. "some_string")' do
@@ -161,7 +161,7 @@
     context 'with an invalid value (ex. "some_string")' do
       let(:value) { 'some_string' }
 
-      it { is_expected.to eq nil }
+      it { is_expected.to be_nil }
     end
 
     context 'with a valid value (ex. " bOlD ")' do