diff --git a/modules/system/assets/ui/docs/select.md b/modules/system/assets/ui/docs/select.md
index b31804f9f..871698389 100644
--- a/modules/system/assets/ui/docs/select.md
+++ b/modules/system/assets/ui/docs/select.md
@@ -66,7 +66,7 @@ Use the `data-handler` attribute to source the select options from an AJAX handl
     class="form-control custom-select"
     data-handler="onGetOptions"
     data-minimum-input-length="2"
-    data-ajax-delay="300"
+    data-ajax--delay="300"
     data-request-data="foo: 'bar'"
 ></select>
 ```