diff --git a/modules/saml/src/Controller/SingleLogout.php b/modules/saml/src/Controller/SingleLogout.php
index 30918bcde8bc5406eb3a2d815501ce50cbce37d3..cf8a4784d5ba08edf1b3f285a6407724a6bae37d 100644
--- a/modules/saml/src/Controller/SingleLogout.php
+++ b/modules/saml/src/Controller/SingleLogout.php
@@ -35,7 +35,7 @@ class SingleLogout
      * @var \SimpleSAML\IdP
      * @psalm-var \SimpleSAML\IdP|class-string
      */
-    protected IdP $idp;
+    protected $idp = IdP::class;
 
 
     /**