diff --git a/lib/yard/templates/helpers/html_helper.rb b/lib/yard/templates/helpers/html_helper.rb
index 850d842c0..f0b76c95c 100644
--- a/lib/yard/templates/helpers/html_helper.rb
+++ b/lib/yard/templates/helpers/html_helper.rb
@@ -93,7 +93,9 @@ def html_markup_markdown(text)
                              :tables,
                              :with_toc_data,
                              :no_intraemphasis).to_html
-        when 'CommonMarker'
+        when 'Commonmarker' # GFM configs are on by default; use YARD for syntax highlighting
+          Commonmarker.to_html(text, options: { extension: { header_ids: nil } }, plugins: {syntax_highlighter: nil})
+        when 'CommonMarker' # old, pre 1.0; downstream consumers should upgrade
           CommonMarker.render_html(text, %i[DEFAULT GITHUB_PRE_LANG], %i[autolink table])
         else
           provider.new(text).to_html
diff --git a/lib/yard/templates/helpers/markup_helper.rb b/lib/yard/templates/helpers/markup_helper.rb
index 9d7a6dcd1..dddc5d395 100644
--- a/lib/yard/templates/helpers/markup_helper.rb
+++ b/lib/yard/templates/helpers/markup_helper.rb
@@ -30,7 +30,7 @@ def clear_markup_cache
           {:lib => :maruku, :const => 'Maruku'},
           {:lib => :'rpeg-markdown', :const => 'PEGMarkdown'},
           {:lib => :rdoc, :const => 'YARD::Templates::Helpers::Markup::RDocMarkdown'},
-          {:lib => :commonmarker, :const => 'CommonMarker'}
+          {:lib => :commonmarker, :const => defined?(CommonMarker) ? 'CommonMarker' : "Commonmarker" }
         ],
         :textile => [
           {:lib => :redcloth, :const => 'RedCloth'}
diff --git a/spec/templates/markup_processor_integrations/markdown_spec.rb b/spec/templates/markup_processor_integrations/markdown_spec.rb
index 8581f7dd8..ca91cf2a5 100644
--- a/spec/templates/markup_processor_integrations/markdown_spec.rb
+++ b/spec/templates/markup_processor_integrations/markdown_spec.rb
@@ -82,7 +82,7 @@
     end
   end
 
-  describe 'CommonMarker', if:  RUBY_VERSION >= '2.3' do
+  describe defined?(CommonMarker) ? 'CommonMarker' : "Commonmarker", if:  RUBY_VERSION >= '2.3' do
     let(:markup) { :markdown }
     let(:markup_provider) { :commonmarker }