diff --git a/essay/sawtooth.html b/essay/sawtooth.html
index d011443..fdcb7ec 100644
--- a/essay/sawtooth.html
+++ b/essay/sawtooth.html
@@ -3,7 +3,10 @@
   <title>Sawtooth</title>
 </head>
 <body>
-  The simplest audible program is
+  [Fork <a href="https://github.com/darius/bytebeat">darius/bytebeat</a>
+  to help write this tutorial.]
+
+  <p>The simplest audible program is
   <form id="form">
     <input id="code0" type="text" size="40" value="t">
     <input id="play" type="submit" value="Play it">
