diff --git a/lib/SimpleSAML/Session.php b/lib/SimpleSAML/Session.php
index 8d4142265c78a8ec24d5637f85925f1988447e6f..9f4a623198c30e553b9b54116421f8b74af9843f 100644
--- a/lib/SimpleSAML/Session.php
+++ b/lib/SimpleSAML/Session.php
@@ -485,11 +485,11 @@ class SimpleSAML_Session {
 			$data = array();
 		}
 
+		$globalConfig = SimpleSAML_Configuration::getInstance();
 		if (!isset($data['AuthnInstant'])) {
 			$data['AuthnInstant'] = time();
 		}
 		if (!isset($data['Expire'])) {
-			$globalConfig = SimpleSAML_Configuration::getInstance();
 			$data['Expire'] = time() + $globalConfig->getInteger('session.duration', 8*60*60);
 		}