diff --git a/examples/config.yml b/examples/config.yml
index f7d45fb..c46fb1b 100644
--- a/examples/config.yml
+++ b/examples/config.yml
@@ -61,7 +61,7 @@ http:
   <<: *css_classes
   format: html
   relative_urls: true
-  chapter_anchor_prefix: 'chapter-'
+  chapter_anchor_prefix: 'chapter'
 
 rss:
   <<: *paths
diff --git a/lib/repubmark/elems/chapter.rb b/lib/repubmark/elems/chapter.rb
index 1cb8a34..e13b72c 100644
--- a/lib/repubmark/elems/chapter.rb
+++ b/lib/repubmark/elems/chapter.rb
@@ -119,7 +119,7 @@ module Repubmark
 
       def build_title_html
         anchor_prefix = String(config[:chapter_anchor_prefix]).strip
-        anchor = %( id="#{anchor_prefix}#@slug") unless anchor_prefix.empty?
+        anchor = %( id="#{anchor_prefix}-#@slug") unless anchor_prefix.empty?
         "<h#@level#{anchor}>#@title</h#@level>\n" if @level != 1
       end