diff --git a/bristlecode.rb b/bristlecode.rb
index 0a06660..1ed7209 100644
--- a/bristlecode.rb
+++ b/bristlecode.rb
@@ -3,11 +3,25 @@ require 'sanitize'
 
 module Bristlecode
 
+  Config = Sanitize::Config::freeze_config(
+    :elements => %w[b em i strong u a strike br],
+    :attributes => {
+      'a' => ['href']
+    },
+    :add_attributes => {
+      'a' => {'rel' => 'nofollow'}
+    },
+    :protocols => {
+      'a' => {'href' => ['http', 'https', :relative]}
+    }
+  )
+
   def Bristlecode.to_html(text)
     parser = Bristlecode::Parser.new
     parse_tree = parser.parse(text)
     tree = Bristlecode::Transform.new.apply(parse_tree)
-    tree.to_html
+    html = tree.to_html
+    Sanitize.fragment(html, Bristlecode::Config)
   end
 
   def Bristlecode.clean(text)
diff --git a/spec/bristlecode/parser_spec.rb b/spec/bristlecode/parser_spec.rb
index 02a488d..07a1e75 100644
--- a/spec/bristlecode/parser_spec.rb
+++ b/spec/bristlecode/parser_spec.rb
@@ -21,9 +21,6 @@ module Bristlecode
       expect(to_html('&')).to eq('&')
       expect(to_html('>')).to eq('>')
       expect(to_html('<')).to eq('&lt;')
-      expect(to_html("'")).to eq('&#x27;')
-      expect(to_html('"')).to eq('&quot;')
-      expect(to_html('/')).to eq('&#x2F;')
     end
 
     it 'handles plain text just fine' do
@@ -57,23 +54,23 @@ module Bristlecode
 
     it 'can render simple links' do
       input = '[url]http://example.com[/url]'
-      output = '<a href="http://example.com">http:&#x2F;&#x2F;example.com</a>'
+      output = '<a href="http://example.com" rel="nofollow">http://example.com</a>'
       expect(to_html(input)).to eq(output)
 
       input = '[url]    http://example.com    [/url]'
-      output = '<a href="http://example.com">http:&#x2F;&#x2F;example.com</a>'
+      output = '<a href="http://example.com" rel="nofollow">http://example.com</a>'
       expect(to_html(input)).to eq(output)
     end
 
     it 'passes simple url contents opaquely' do
       input = '[url]http://x[b]y[/b]z[/url]'
-      output = '<a href="http://x[b]y[/b]z">http:&#x2F;&#x2F;x[b]y[&#x2F;b]z</a>'
+      output = '<a href="http://x%5Bb%5Dy%5B/b%5Dz" rel="nofollow">http://x[b]y[/b]z</a>'
       expect(to_html(input)).to eq(output)
     end
 
     it 'handles urls with titles' do
       input = '[url=http://google.com]the google[/url]'
-      output = '<a href="http://google.com">the google</a>'
+      output = '<a href="http://google.com" rel="nofollow">the google</a>'
       expect(to_html(input)).to eq(output)
     end