diff --git a/index.html b/index.html
index 2925eb962e1dbce0900613996afa8de44e42c62e..8bbd19844f82d368a72239810e48ba97f9288fec 100644
--- a/index.html
+++ b/index.html
@@ -60,6 +60,13 @@ The GPIO test measures how quickly pins can communicate with a processor core; t
 <td>December, 2020</td>
 </tr>
 
+<tr>
+<td>3.737</td>
+<td>ATSAMD51</td>
+<td><a href=prior/gpio/atsamd51/index.html>PORT</a></td>
+<td>November, 2018</td>
+</tr>
+
 <tr>
 <td>2.528</td>
 <td>ATSAMD11C</td>