diff --git a/lib/Doctrine/Common/Persistence/AbstractManagerRegistry.php b/lib/Doctrine/Common/Persistence/AbstractManagerRegistry.php
index 3839e74c..53fd28ce 100644
--- a/lib/Doctrine/Common/Persistence/AbstractManagerRegistry.php
+++ b/lib/Doctrine/Common/Persistence/AbstractManagerRegistry.php
@@ -235,7 +235,7 @@ public function resetManager($name = null)
         return $this->getManager($name);
     }
 
-    private function selectManager(string $persistentObjectName, ?string $persistentManagerName = null) : ?ObjectManager
+    private function selectManager(string $persistentObjectName, ?string $persistentManagerName = null) : ObjectManager
     {
         if ($persistentManagerName !== null) {
             return $this->getManager($persistentManagerName);