diff --git a/tests/ReportTest/FakeObject.php b/tests/ReportTest/FakeObject.php
index 9951b172..5a87b6c5 100644
--- a/tests/ReportTest/FakeObject.php
+++ b/tests/ReportTest/FakeObject.php
@@ -24,7 +24,7 @@ public function Link()
         return Controller::join_links('dummy-link', $this->ID);
     }
 
-    public function CMSEditLink()
+    public function CMSEditLink(): ?string
     {
         return Controller::join_links('dummy-edit-link', $this->ID);
     }