diff --git a/index.html b/index.html
index a78351e..0e2130a 100644
--- a/index.html
+++ b/index.html
@@ -2388,7 +2388,7 @@ <h3>Processing Errors</h3>
 the error.
           </li>
           <li>
-The `detail` value MUST be present and SHOULD provide a longer human-readable [=string=] for the error.
+The `detail` value SHOULD provide a longer human-readable [=string=] for the error.
           </li>
         </ul>