diff --git a/src/test/java/org/jenkins/plugins/lockableresources/ConfigurationAsCodeTest.java b/src/test/java/org/jenkins/plugins/lockableresources/ConfigurationAsCodeTest.java
index 7f393a811..d1fdb5d52 100644
--- a/src/test/java/org/jenkins/plugins/lockableresources/ConfigurationAsCodeTest.java
+++ b/src/test/java/org/jenkins/plugins/lockableresources/ConfigurationAsCodeTest.java
@@ -3,6 +3,8 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import io.jenkins.plugins.casc.ConfigurationAsCode;
 import io.jenkins.plugins.casc.ConfigurationContext;
@@ -16,7 +18,6 @@
 import java.util.Date;
 import java.util.List;
 import org.jenkins.plugins.lockableresources.util.Constants;
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -34,7 +35,7 @@ void setUp() {
     @ConfiguredWithCode("configuration-as-code.yml")
     void should_support_configuration_as_code(JenkinsConfiguredWithCodeRule r) {
         LockableResourcesManager LRM = LockableResourcesManager.get();
-        Assertions.assertTrue(LRM.isAllowEmptyOrNullValues());
+        assertTrue(LRM.isAllowEmptyOrNullValues());
 
         List<LockableResource> declaredResources = LRM.getDeclaredResources();
         assertEquals(
@@ -47,7 +48,7 @@ void should_support_configuration_as_code(JenkinsConfiguredWithCodeRule r) {
         assertEquals("Description_A", declaredResource.getDescription());
         assertEquals("Label_A", declaredResource.getLabels());
         // not supported in JCaC
-        assertEquals(null, declaredResource.getReservedBy());
+        assertNull(declaredResource.getReservedBy());
         assertEquals("", declaredResource.getNote());
 
         assertEquals(
@@ -58,7 +59,7 @@ void should_support_configuration_as_code(JenkinsConfiguredWithCodeRule r) {
         assertEquals("Description_A", resource.getDescription());
         assertEquals("Label_A", resource.getLabels());
         // not supported in JCaC
-        assertEquals(null, declaredResource.getReservedBy());
+        assertNull(declaredResource.getReservedBy());
         assertEquals("", declaredResource.getNote());
     }
 
diff --git a/src/test/java/org/jenkins/plugins/lockableresources/LockStepWithRestartTest.java b/src/test/java/org/jenkins/plugins/lockableresources/LockStepWithRestartTest.java
index 6dcab6284..cd1210a76 100644
--- a/src/test/java/org/jenkins/plugins/lockableresources/LockStepWithRestartTest.java
+++ b/src/test/java/org/jenkins/plugins/lockableresources/LockStepWithRestartTest.java
@@ -1,6 +1,6 @@
 package org.jenkins.plugins.lockableresources;
 
-import static org.junit.Assert.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 import hudson.model.FreeStyleBuild;
 import hudson.model.FreeStyleProject;
@@ -11,20 +11,20 @@
 import org.jenkinsci.plugins.workflow.job.WorkflowJob;
 import org.jenkinsci.plugins.workflow.job.WorkflowRun;
 import org.jenkinsci.plugins.workflow.test.steps.SemaphoreStep;
-import org.junit.Rule;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
 import org.jvnet.hudson.test.JenkinsRule;
-import org.jvnet.hudson.test.JenkinsSessionRule;
+import org.jvnet.hudson.test.junit.jupiter.JenkinsSessionExtension;
 
-public class LockStepWithRestartTest extends LockStepTestBase {
+class LockStepWithRestartTest extends LockStepTestBase {
 
     private static final Logger LOGGER = Logger.getLogger(LockStepTestBase.class.getName());
 
-    @Rule
-    public JenkinsSessionRule sessions = new JenkinsSessionRule();
+    @RegisterExtension
+    private final JenkinsSessionExtension sessions = new JenkinsSessionExtension();
 
     @Test
-    public void lockOrderRestart() throws Throwable {
+    void lockOrderRestart() throws Throwable {
         sessions.then(j -> {
             LockableResourcesManager.get().createResource("resource1");
             WorkflowJob p = j.jenkins.createProject(WorkflowJob.class, "p");
@@ -73,7 +73,7 @@ public void lockOrderRestart() throws Throwable {
     }
 
     @Test
-    public void interoperabilityOnRestart() throws Throwable {
+    void interoperabilityOnRestart() throws Throwable {
         sessions.then(j -> {
             LockableResourcesManager.get().createResource("resource1");
             WorkflowJob p = j.jenkins.createProject(WorkflowJob.class, "p");
@@ -120,7 +120,7 @@ public void interoperabilityOnRestart() throws Throwable {
     }
 
     @Test
-    public void testReserveOverRestart() throws Throwable {
+    void testReserveOverRestart() throws Throwable {
         sessions.then(j -> {
             LockableResourcesManager manager = LockableResourcesManager.get();
             manager.createResource("resource1");
@@ -163,7 +163,7 @@ public void testReserveOverRestart() throws Throwable {
     }
 
     @Test
-    public void checkQueueAfterRestart() throws Throwable {
+    void checkQueueAfterRestart() throws Throwable {
         sessions.then(j -> {
             LockableResourcesManager lrm = LockableResourcesManager.get();
 
@@ -206,7 +206,7 @@ public void checkQueueAfterRestart() throws Throwable {
     }
 
     @Test
-    public void chaosOnRestart() throws Throwable {
+    void chaosOnRestart() throws Throwable {
         final int resourceCount = 50;
         sessions.then(j -> {
             for (int i = 1; i <= resourceCount; i++) {