diff --git a/src/Models/BaseElement.php b/src/Models/BaseElement.php
index 16513727..6c25ac61 100644
--- a/src/Models/BaseElement.php
+++ b/src/Models/BaseElement.php
@@ -888,7 +888,7 @@ public function isCMSPreview()
      * @return null|string
      * @throws \SilverStripe\ORM\ValidationException
      */
-    public function CMSEditLink($directLink = false)
+    public function CMSEditLink($directLink = false): ?string
     {
         // Allow for repeated calls to be returned from cache
         if (isset($this->cacheData['cms_edit_link'])) {