diff --git a/src/Server/ResourceServer.php b/src/Server/ResourceServer.php
index 20ec74fed092604d1da12c007566dc68fe4d9303..ec782cd253764b60fd3e56b4d59d18f4265ab19b 100644
--- a/src/Server/ResourceServer.php
+++ b/src/Server/ResourceServer.php
@@ -22,7 +22,7 @@ class ResourceServer implements ResourceServerInterface {
    *
    * @var \League\OAuth2\Server\ResourceServer|null
    */
-  protected ?LeagueResourceServer $subject;
+  protected ?LeagueResourceServer $subject = NULL;
 
   /**
    * The message factory.