diff --git a/.travis.yml b/.travis.yml
index 912323b..3b1ba50 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,9 @@ rvm:
   - 2.2
   - 2.3.1
   - 2.4.0
-# Put this in your .travis.yml
+# gemfile is generated by appraisal
 gemfile:
+  - gemfiles/jekyll_3.4.gemfile
   - gemfiles/jekyll_3.3.gemfile
   - gemfiles/jekyll_3.2.gemfile
   - gemfiles/jekyll_3.1.gemfile
diff --git a/README.md b/README.md
index cbaa1c6..a1992fb 100644
--- a/README.md
+++ b/README.md
@@ -37,19 +37,19 @@ There are three Liquid filters available now, which all should be applied
 to some HTML content, e.g. the Liquid variable `content` available in
 Jekyll's templates.
 
-## Basic Usage
+## 1. Basic Usage
 
 ### `toc` filter
 
 Add `toc` filter to your site's `{{ content }}` (e.g. `_layouts/post.html`).
 
-```
+```liquid
 {{ content | toc }}
 ```
 
 This filter places the TOC directly above the content.
 
-## Advanced Usage
+## 2. Advanced Usage
 
 If you'd like separated TOC and content, you can use `toc_only` and `inject_anchors` filters.
 
diff --git a/lib/table_of_contents/parser.rb b/lib/table_of_contents/parser.rb
index 34b149f..17e9795 100644
--- a/lib/table_of_contents/parser.rb
+++ b/lib/table_of_contents/parser.rb
@@ -1,7 +1,8 @@
 module Jekyll
   module TableOfContents
+    # Parse html contents and generate table of contents
     class Parser
-      PUNCTUATION_REGEXP = RUBY_VERSION > '1.9' ? /[^\p{Word}\- ]/u : /[^\w\- ]/
+      PUNCTUATION_REGEXP = /[^\p{Word}\- ]/u
 
       attr_reader :doc
 
@@ -11,11 +12,11 @@ def initialize(html)
       end
 
       def build_toc
-        toc = %Q{<ul class="section-nav">\n}
+        toc = %(<ul class="section-nav">\n)
 
         min_h_num = 6
         @entries.each do |entry|
-          h_num = entry[:node_name].delete("h").to_i
+          h_num = entry[:node_name].delete('h').to_i
           min_h_num = [min_h_num, h_num].min
         end
         toc << build_lis(@entries, min_h_num)
@@ -23,42 +24,81 @@ def build_toc
         toc << '</ul>'
       end
 
+      def inject_anchors_into_html
+        @entries.each do |entry|
+          entry[:content_node].add_previous_sibling(%(<a id="#{entry[:id]}#{entry[:uniq]}" class="anchor" href="##{entry[:id]}#{entry[:uniq]}" aria-hidden="true"><span class="octicon octicon-link"></span></a>))
+        end
+
+        @doc.inner_html
+      end
+
+      def toc
+        build_toc + inject_anchors_into_html
+      end
+
+      private
+
+      # parse logic is from html-pipeline toc_filter
+      # https://github.com/jch/html-pipeline/blob/v1.1.0/lib/html/pipeline/toc_filter.rb
+      def parse_content
+        entries = []
+        headers = Hash.new(0)
+
+        @doc.css('h1, h2, h3, h4, h5, h6').each do |node|
+          text = node.text
+          id = text.downcase
+          id.gsub!(PUNCTUATION_REGEXP, '') # remove punctuation
+          id.gsub!(' ', '-') # replace spaces with dash
+
+          uniq = headers[id] > 0 ? "-#{headers[id]}" : ''
+          headers[id] += 1
+          header_content = node.children.first
+          next unless header_content
+
+          entries << {
+            id: id,
+            uniq: uniq,
+            text: text,
+            node_name: node.name,
+            content_node: header_content
+          }
+        end
+
+        entries
+      end
+
       # Returns the list items for entries
       def build_lis(entries, min_h_num)
-        lis = ""
+        lis = ''
         i = 0
-        while i < entries.length do
+        while i < entries.length
           entry = entries[i]
-          curr_h_num = entry[:node_name].delete("h").to_i
+          curr_h_num = entry[:node_name].delete('h').to_i
           if curr_h_num == min_h_num
-            
             # If the current entry should not be indented in the list, add the entry to the list
-            lis << %Q{<li class="toc-entry toc-#{entry[:node_name]}"><a href="##{entry[:id]}#{entry[:uniq]}">#{entry[:text]}</a>}
+            lis << %(<li class="toc-entry toc-#{entry[:node_name]}"><a href="##{entry[:id]}#{entry[:uniq]}">#{entry[:text]}</a>)
             # If the next entry should be indented in the list, generate a sublist
             if i + 1 < entries.length
               next_entry = entries[i + 1]
-              next_h_num = next_entry[:node_name].delete("h").to_i
+              next_h_num = next_entry[:node_name].delete('h').to_i
               if next_h_num > min_h_num
-                lis << %Q{\n}
-                lis << %Q{<ul>\n}
+                lis << %(\n)
+                lis << %(<ul>\n)
                 nest_entries = get_nest_entries(entries[i + 1, entries.length], min_h_num)
                 lis << build_lis(nest_entries, min_h_num + 1)
-                lis << %Q{</ul>\n}
+                lis << %(</ul>\n)
                 i += nest_entries.length
               end
             end
             # Add the closing tag for the current entry in the list
-            lis << %Q{</li>\n}
-            
+            lis << %(</li>\n)
           elsif curr_h_num > min_h_num
-          
             # If the current entry should be indented in the list, generate a sublist
-            lis << %Q{<ul>\n}
+            lis << %(<ul>\n)
             nest_entries = get_nest_entries(entries[i, entries.length], min_h_num)
             lis << build_lis(nest_entries, min_h_num + 1)
-            lis << %Q{</ul>\n}
+            lis << %(</ul>\n)
             i += nest_entries.length - 1
-            
           end
           i += 1
         end
@@ -70,59 +110,14 @@ def build_lis(entries, min_h_num)
       # The nested list ends at the first entry in entries with depth min_h_num or greater (exclusive)
       def get_nest_entries(entries, min_h_num)
         nest_entries = []
-        for i in 0..(entries.length - 1)
+        (0..(entries.length - 1)).each do |i|
           nest_entry = entries[i]
-          nest_h_num = nest_entry[:node_name].delete("h").to_i
-          if nest_h_num > min_h_num
-            nest_entries.push(nest_entry)
-          else
-            break
-          end
+          nest_h_num = nest_entry[:node_name].delete('h').to_i
+          break unless nest_h_num > min_h_num
+          nest_entries.push(nest_entry)
         end
         nest_entries
       end
-
-      def inject_anchors_into_html
-        @entries.each do |entry|
-          entry[:content_node].add_previous_sibling(%Q{<a id="#{entry[:id]}#{entry[:uniq]}" class="anchor" href="##{entry[:id]}#{entry[:uniq]}" aria-hidden="true"><span class="octicon octicon-link"></span></a>})
-        end
-
-        @doc.inner_html
-      end
-
-      def toc
-        build_toc + inject_anchors_into_html
-      end
-
-      # parse logic is from html-pipeline toc_filter
-      # https://github.com/jch/html-pipeline/blob/v1.1.0/lib/html/pipeline/toc_filter.rb
-      private
-
-      def parse_content
-        entries = []
-        headers = Hash.new(0)
-
-        @doc.css('h1, h2, h3, h4, h5, h6').each do |node|
-          text = node.text
-          id = text.downcase
-          id.gsub!(PUNCTUATION_REGEXP, '') # remove punctuation
-          id.gsub!(' ', '-') # replace spaces with dash
-
-          uniq = (headers[id] > 0) ? "-#{headers[id]}" : ''
-          headers[id] += 1
-          if header_content = node.children.first
-            entries << {
-                id: id,
-                uniq: uniq,
-                text: text,
-                node_name: node.name,
-                content_node: header_content
-            }
-          end
-        end
-
-        entries
-      end
     end
   end
 end
diff --git a/lib/version.rb b/lib/version.rb
index 628843c..62bb2b8 100644
--- a/lib/version.rb
+++ b/lib/version.rb
@@ -1,3 +1,3 @@
 module JekyllToc
-  VERSION = '0.2.1'
+  VERSION = '0.3.0.pre1'
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 54398f9..bd15e2f 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -4,14 +4,14 @@
 require 'jekyll'
 require 'minitest/autorun'
 
-SIMPLE_HTML = <<EOL
+SIMPLE_HTML = <<HTML
 <h1>Simple H1</h1>
 <h2>Simple H2</h2>
 <h3>Simple H3</h3>
 <h4>Simple H4</h4>
 <h5>Simple H5</h5>
 <h6>Simple H6</h6>
-EOL
+HTML
 
 module TestHelpers
   def read_html_and_create_parser