diff --git a/modules/saml2/lib/Message.php b/modules/saml2/lib/Message.php
index 8c7ffa06072189d06c623357af5ed34b6f43a0b3..1b049fadf6a8ceea55fa56f238af642c950af9e1 100644
--- a/modules/saml2/lib/Message.php
+++ b/modules/saml2/lib/Message.php
@@ -582,10 +582,13 @@ class sspmod_saml2_Message {
 
 		$a->setAuthnContext(SAML2_Const::AC_PASSWORD);
 
+		$session = SimpleSAML_Session::getInstance();
+
+		$a->setAuthnInstant($session->getAuthnInstant());
+
 		$sessionLifetime = $config->getInteger('session.duration', 8*60*60);
 		$a->setSessionNotOnOrAfter(time() + $sessionLifetime);
 
-		$session = SimpleSAML_Session::getInstance();
 		$sessionIndex = $session->getSessionIndex();
 		$a->setSessionIndex($sessionIndex);