diff --git a/docs/USING_PRO.md b/docs/USING_PRO.md
index 012f7634e8..2966aabf73 100644
--- a/docs/USING_PRO.md
+++ b/docs/USING_PRO.md
@@ -288,7 +288,7 @@ console.log(marked('# heading 2\n\n## heading 3'));
 
 ***
 
-<h2>Custom Extensions : <code>extensions</code></h2>
+<h2 id="extensions">Custom Extensions : <code>extensions</code></h2>
 
 You may supply an `extensions` array to the `options` object. This array can contain any number of `extension` objects, using the following properties:
 
diff --git a/docs/_document.html b/docs/_document.html
index bec1adc854..3527ebc1e9 100644
--- a/docs/_document.html
+++ b/docs/_document.html
@@ -50,6 +50,7 @@ <h1>Marked Documentation</h1>
                             <li><a href="/using_pro#renderer">Renderer</a></li>
                             <li><a href="/using_pro#tokenizer">Tokenizer</a></li>
                             <li><a href="/using_pro#walk-tokens">Walk Tokens</a></li>
+                            <li><a href="/using_pro#extensions">Custom Extensions</a></li>
                             <li><a href="/using_pro#lexer">Lexer</a></li>
                             <li><a href="/using_pro#parser">Parser</a></li>
                         </ul>