diff --git a/lib/SimpleSAML/Session.php b/lib/SimpleSAML/Session.php
index 439252793d72590e86c2a4eec18682b3b4dee531..99bde5aad70844988c22aaae15c82a4022708292 100644
--- a/lib/SimpleSAML/Session.php
+++ b/lib/SimpleSAML/Session.php
@@ -463,6 +463,7 @@ class SimpleSAML_Session {
 	 */
 	public function registerLogoutHandler($file, $classname, $functionname) {
 		$this->logout_handlers[] = array('file' => $file, 'class' => $classname, 'function' => $functionname);
+		$this->dirty = TRUE;
 	}