diff --git a/library/Reporting/Hook/EmailProviderHook.php b/library/Reporting/Hook/EmailProviderHook.php
index 4f76c9de..2a0dddc2 100644
--- a/library/Reporting/Hook/EmailProviderHook.php
+++ b/library/Reporting/Hook/EmailProviderHook.php
@@ -9,9 +9,9 @@ abstract class EmailProviderHook
     /**
      * Get all Contact eMails
      *
-     * @return mixed
+     * @return array
      */
-    abstract public function getContactEmails();
+    abstract public function getContactEmails(): array;
 
     /**
      * @return array