diff --git a/.ci.gemfile b/.ci.gemfile
index 83f4e2b..2754b4e 100644
--- a/.ci.gemfile
+++ b/.ci.gemfile
@@ -74,7 +74,8 @@ platform :ruby do
   gem 'rinku' # dependency for wikicloth for handling links
 
   gem 'RedCloth'
-  gem 'commonmarker', '< 1'
+  gem 'commonmarker'
+
   gem 'rdiscount', '>= 2.1.6'
   gem 'redcarpet'
   gem 'yajl-ruby'
diff --git a/lib/tilt/commonmarker.rb b/lib/tilt/commonmarker.rb
index d404744..6693aa5 100644
--- a/lib/tilt/commonmarker.rb
+++ b/lib/tilt/commonmarker.rb
@@ -2,53 +2,92 @@
 require_relative 'template'
 require 'commonmarker'
 
-aliases = {
-  :smartypants => :SMART
-}.freeze
-parse_opts = [
-  :FOOTNOTES,
-  :LIBERAL_HTML_TAG,
-  :SMART,
-  :smartypants,
-  :STRIKETHROUGH_DOUBLE_TILDE,
-  :UNSAFE,
-  :VALIDATE_UTF8,
-].freeze
-render_opts = [
-  :FOOTNOTES,
-  :FULL_INFO_STRING,
-  :GITHUB_PRE_LANG,
-  :HARDBREAKS,
-  :NOBREAKS,
-  :SAFE, # Removed in v0.18.0 (2018-10-17)
-  :SOURCEPOS,
-  :TABLE_PREFER_STYLE_ATTRIBUTES,
-  :UNSAFE,
-].freeze
-exts = [
-  :autolink,
-  :strikethrough,
-  :table,
-  :tagfilter,
-  :tasklist,
-].freeze
+if defined?(::Commonmarker)
+  aliases = {
+    :smartypants => :smart
+  }.freeze
+  parse_opts = [
+    :smart,
+    :default_info_string,
+  ].freeze
+  render_opts = [
+    :hardbreaks,
+    :github_pre_lang,
+    :width,
+    :unsafe,
+    :escape,
+    :sourcepos,
+  ].freeze
+  exts = [
+    :strikethrough,
+    :tagfilter,
+    :table,
+    :autolink,
+    :tasklist,
+    :superscript,
+    :header_ids,
+    :footnotes,
+    :description_lists,
+    :front_matter_delimiter,
+    :shortcodes,
+  ].freeze
 
+  Tilt::CommonMarkerTemplate = Tilt::StaticTemplate.subclass do
+    parse_options = @options.select { |key, _| parse_opts.include?(key.downcase) }.transform_keys(&:downcase)
+    parse_options.merge!(@options.select { |key, _| aliases.has_key?(key) }.transform_keys { |key| aliases[key] })
+    render_options = @options.select { |key, _| render_opts.include?(key.downcase) }.transform_keys(&:downcase)
+    extensions = @options.select { |key, _| exts.include?(key) }.transform_keys(&:downcase)
 
-Tilt::CommonMarkerTemplate = Tilt::StaticTemplate.subclass do
-  extensions = exts.select do |extension|
-    @options[extension]
+    Commonmarker.to_html(@data, options: { parse: parse_options, render: render_options, extension: extensions })
   end
+else
+  aliases = {
+    :smartypants => :SMART
+  }.freeze
+  parse_opts = [
+    :FOOTNOTES,
+    :LIBERAL_HTML_TAG,
+    :SMART,
+    :smartypants,
+    :STRIKETHROUGH_DOUBLE_TILDE,
+    :UNSAFE,
+    :VALIDATE_UTF8,
+  ].freeze
+  render_opts = [
+    :FOOTNOTES,
+    :FULL_INFO_STRING,
+    :GITHUB_PRE_LANG,
+    :HARDBREAKS,
+    :NOBREAKS,
+    :SAFE, # Removed in v0.18.0 (2018-10-17)
+    :SOURCEPOS,
+    :TABLE_PREFER_STYLE_ATTRIBUTES,
+    :UNSAFE,
+  ].freeze
+  exts = [
+    :autolink,
+    :strikethrough,
+    :table,
+    :tagfilter,
+    :tasklist,
+  ].freeze
 
-  parse_options, render_options = [parse_opts, render_opts].map do |opts|
-    opts = opts.select do |option|
-      @options[option]
-    end.map! do |option|
-      aliases[option] || option
+  Tilt::CommonMarkerTemplate = Tilt::StaticTemplate.subclass do
+    extensions = exts.select do |extension|
+      @options[extension]
     end
 
-    opts = :DEFAULT unless opts.any?
-    opts
-  end
+    parse_options, render_options = [parse_opts, render_opts].map do |opts|
+      opts = opts.select do |option|
+        @options[option]
+      end.map! do |option|
+        aliases[option] || option
+      end
+
+      opts = :DEFAULT unless opts.any?
+      opts
+    end
 
-  CommonMarker.render_doc(@data, parse_options, extensions).to_html(render_options, extensions)
+    CommonMarker.render_doc(@data, parse_options, extensions).to_html(render_options, extensions)
+  end
 end
diff --git a/test/tilt_commonmarkertemplate_test.rb b/test/tilt_commonmarkertemplate_test.rb
index c381e81..ba1c86b 100644
--- a/test/tilt_commonmarkertemplate_test.rb
+++ b/test/tilt_commonmarkertemplate_test.rb
@@ -44,4 +44,46 @@
   it "sets allows_script metadata set to false" do
     assert_equal false, Tilt::CommonMarkerTemplate.new { |t| "# Hello World!" }.metadata[:allows_script]
   end
+
+  if defined?(::Commonmarker)
+    it "render unsafe HTML with pre version's option name" do
+      template = Tilt::CommonMarkerTemplate.new(UNSAFE: true) do |_t|
+        <<MARKDOWN
+<div class="alert alert-info full-width">
+<h5 class="card-title">TL;DR</h5>
+<p>This is an unsafe HTML block</p>
+</div>
+
+And then some **other** Markdown
+MARKDOWN
+      end
+
+      expected = <<EXPECTED_HTML
+<div class="alert alert-info full-width">
+<h5 class="card-title">TL;DR</h5>
+<p>This is an unsafe HTML block</p>
+</div>
+<p>And then some <strong>other</strong> Markdown</p>
+EXPECTED_HTML
+
+      assert_match(expected, template.render)
+    end
+
+    it "smartypants when :smartypants is set (pre version's option name)" do
+      template = Tilt::CommonMarkerTemplate.new(:smartypants => true) do |t|
+        "OKAY -- 'Smarty Pants'"
+      end
+      assert_match('<p>OKAY – ‘Smarty Pants’</p>', template.render)
+    end
+
+    it "render markdown with custom prefixed-header id" do
+      template = Tilt::CommonMarkerTemplate.new(header_ids: "prefix-") do |t|
+        "# Foo"
+      end
+      expected = <<HTML
+<h1><a href="#foo" aria-hidden="true" class="anchor" id="prefix-foo"></a>Foo</h1>
+HTML
+      assert_match(expected, template.render)
+    end
+  end
 end