diff --git a/tests/Ion/mocks.php b/tests/Ion/mocks.php
index 0a28b385..c0a2f755 100644
--- a/tests/Ion/mocks.php
+++ b/tests/Ion/mocks.php
@@ -66,7 +66,7 @@ class FriendTestClass extends FriendParentTestClass {
 
 class TestTransformer extends AbstractTransformer {
 
-	public function transform($item)
+	public function transform(array|object $item): array
 	{
 		$out = [];
 		$genre_list = (array) $item;