diff --git a/src/Doctrine/Purger/DoNotUsePurgerFactory.php b/src/Doctrine/Purger/DoNotUsePurgerFactory.php
index 95726fab..6d487573 100644
--- a/src/Doctrine/Purger/DoNotUsePurgerFactory.php
+++ b/src/Doctrine/Purger/DoNotUsePurgerFactory.php
@@ -44,7 +44,7 @@ class DoNotUsePurgerFactory implements PurgerFactory
                 throw new \LogicException('Do not use doctrine:fixtures:load directly. Use partdb:fixtures:load instead!');
             }
 
-            public function setEntityManager(EntityManagerInterface $em)
+            public function setEntityManager(EntityManagerInterface $em): void
             {
                 // TODO: Implement setEntityManager() method.
             }