diff --git a/lib/Froxlor/Api/Commands/Certificates.php b/lib/Froxlor/Api/Commands/Certificates.php
index 7a9adac0..0b9b9505 100644
--- a/lib/Froxlor/Api/Commands/Certificates.php
+++ b/lib/Froxlor/Api/Commands/Certificates.php
@@ -293,7 +293,7 @@ class Certificates extends \Froxlor\Api\ApiCommand implements \Froxlor\Api\Resou
 		}
 
 		$do_verify = true;
-		$expirationdate = NULL;
+		$expirationdate = null;
 		// no cert-file given -> forget everything
 		if ($ssl_cert_file == '') {
 			$ssl_key_file = '';
@@ -334,7 +334,7 @@ class Certificates extends \Froxlor\Api\ApiCommand implements \Froxlor\Api\Resou
 			} else {
 				\Froxlor\UI\Response::standard_error('sslcertificateinvalidcert', '', true);
 			}
-			$expirationdate = $cert_content['validTo_time_t'];
+			$expirationdate = empty($cert_content['validTo_time_t']) ? null : $date("Y-m-d H:i:s", $cert_content['validTo_time_t']);
 		}
 
 		// Add/Update database entry
@@ -357,7 +357,7 @@ class Certificates extends \Froxlor\Api\ApiCommand implements \Froxlor\Api\Resou
 			"ssl_key_file" => $ssl_key_file,
 			"ssl_ca_file" => $ssl_ca_file,
 			"ssl_cert_chainfile" => $ssl_cert_chainfile,
-			"expirationdate" => date("Y-m-d H:i:s", $expirationdate),
+			"expirationdate" => $expirationdate,
 			"domainid" => $domainid
 		);
 		Database::pexecute($stmt, $params, true, true);