diff --git a/Jenkinsfile b/Jenkinsfile
index 3bab72b6..337d2a5a 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -12,7 +12,7 @@ pipeline {
             steps {
                 script {
                     m2repo = "${pwd tmp: true}/m2repo"
-                    String jdk = "11"
+                    String jdk = "21"
                     List<String> mavenOptions = [
                             '--update-snapshots',
                             "-Dmaven.repo.local=$m2repo",
diff --git a/test/com/trilead/ssh2/KnownHostsTest.java b/test/com/trilead/ssh2/KnownHostsTest.java
index 1d0effeb..c3a4d29a 100644
--- a/test/com/trilead/ssh2/KnownHostsTest.java
+++ b/test/com/trilead/ssh2/KnownHostsTest.java
@@ -43,6 +43,7 @@ public void testKnownHostsPreferredAlgorithmsSshRsaOnly() throws IOException, No
     public void testKnownHostsPreferredAlgorithmsEcdsaOnly() throws IOException, NoSuchAlgorithmException {
         KnownHosts testCase = new KnownHosts();
         KeyPairGenerator ecGenerator = KeyPairGenerator.getInstance("EC");
+        ecGenerator.initialize(256);
         testCase.addHostkey(new String[]{"localhost"}, "ecdsa-sha2-nistp256", new ECDSAKeyAlgorithm.ECDSASha2Nistp256().encodePublicKey((ECPublicKey) ecGenerator.generateKeyPair().getPublic()));
         assertArrayEquals(new String[]{"ecdsa-sha2-nistp256", "ssh-ed25519", "ecdsa-sha2-nistp521", "ecdsa-sha2-nistp384","rsa-sha2-256", "rsa-sha2-512","ssh-rsa", "ssh-dss"}, testCase.getPreferredServerHostkeyAlgorithmOrder("localhost"));
     }