diff --git a/lib/SAML2/Assertion.php b/lib/SAML2/Assertion.php
index be4b8ea351368c5af8332c7947050e2eeab53be3..e08c87e5a4c71ff479ca1eff6f7d760bd0ca12b5 100644
--- a/lib/SAML2/Assertion.php
+++ b/lib/SAML2/Assertion.php
@@ -948,9 +948,6 @@ class SAML2_Assertion implements SAML2_SignedElement {
 		$scd = $root->ownerDocument->createElementNS(SAML2_Const::NS_SAML, 'saml:SubjectConfirmationData');
 		$sc->appendChild($scd);
 
-		if ($this->notBefore !== NULL) {
-			$scd->setAttribute('NotBefore', gmdate('Y-m-d\TH:i:s\Z', $this->notBefore));
-		}
 		if ($this->notOnOrAfter !== NULL) {
 			$scd->setAttribute('NotOnOrAfter', gmdate('Y-m-d\TH:i:s\Z', $this->notOnOrAfter));
 		}