diff --git a/webprofiler/src/Entity/Decorators/Config/ConfigEntityStorageDecorator.php b/webprofiler/src/Entity/Decorators/Config/ConfigEntityStorageDecorator.php
index d842b8294cbbfdb50f8881cdcaa1f96c69779838..192fcc6acb447c4944faa8fae1c067d3ec88531e 100644
--- a/webprofiler/src/Entity/Decorators/Config/ConfigEntityStorageDecorator.php
+++ b/webprofiler/src/Entity/Decorators/Config/ConfigEntityStorageDecorator.php
@@ -229,7 +229,7 @@ class ConfigEntityStorageDecorator extends EntityDecorator implements ConfigEnti
   /**
    * {@inheritdoc}
    */
-  public function getEntityClass($bundle = NULL) {
+  public function getEntityClass(?string $bundle = NULL) : string {
     return $this->getOriginalObject()->getEntityClass($bundle);
   }