diff --git a/aria-practices.html b/aria-practices.html
index cfba20928a..6812960892 100644
--- a/aria-practices.html
+++ b/aria-practices.html
@@ -2269,6 +2269,10 @@ <h4>WAI-ARIA Roles, States, and Properties</h4>
             Otherwise, the spinbutton element has a label provided by
             <a href="#aria-label" class="property-reference">aria-label</a>.
           </li>
+          <li>
+            If it is possible to modify the value of the textbox such that the value is outside of the allowed set of values, the spinbutton element has
+            <a href="#aria-invalid" class="state-reference">aria-invalid</a> set to <code>true</code>.
+          </li>
         </ul>
       </section>
     </section>