diff --git a/modules/backend/formwidgets/TagList.php b/modules/backend/formwidgets/TagList.php
index 8389654108..fdaa2f117e 100644
--- a/modules/backend/formwidgets/TagList.php
+++ b/modules/backend/formwidgets/TagList.php
@@ -121,7 +121,7 @@ public function getSaveValue($value)
      * Returns an array suitable for saving against a relation (array of keys).
      * This method also creates non-existent tags.
      */
-    protected function hydrateRelationSaveValue($names): array
+    protected function hydrateRelationSaveValue($names): ?array
     {
         if (!$names) {
             return $names;