diff --git a/lib/guides/indexer.rb b/lib/guides/indexer.rb
index 4a8d01e..af87333 100644
--- a/lib/guides/indexer.rb
+++ b/lib/guides/indexer.rb
@@ -46,7 +46,7 @@ def process(string, current_level=3, counters=[1])
 
           header_html = Guides.config['index_header'] || "{{index}} {{title}}"
           values = { 'index' => index, 'title' => title }
-          header = header_html.gsub(/{{(.*?)}}/){ values[$1].to_str }
+          header = header_html.gsub(/\{\{(.*?)\}\}/){ values[$1].to_str }
 
           raise "Parsing Fail" unless @result.sub!(s.matched, "h#{level}(#{element_id}). #{header}")