diff --git a/handbook/survey/index.htm b/handbook/survey/index.htm
index d507a0710..376d8c654 100644
--- a/handbook/survey/index.htm
+++ b/handbook/survey/index.htm
@@ -80,7 +80,7 @@ Survey Workshop - <a href="/expofiles/presentations/cave_surveying_20130626.pdf"
   <ul>
     <li><a href="more.htm">Software tools we use</a> </li>
     
-    <li><a href="https://www.cavinguk.co.uk/info/Surveygrade.html">Tarquin's guide to cave surveying</a> BCRA grades </li>
+    <li><a href="https://www.cavinguk.co.uk/info/Surveygrade.htm">Tarquin's guide to cave surveying</a> BCRA grades </li>
     <li><a href="https://www.cavinguk.co.uk/info/sexytopo.html">Tarquin's guide to SexyTopo</a> </li>
   </ul>
 	<li>History of  <a href="../website-history.html">CUCC cave data archiving</a>.</li>