diff --git a/src/main/java/de/cronn/testutils/ExecutorServiceExtension.java b/src/main/java/de/cronn/testutils/ExecutorServiceExtension.java
index b37ca0a..754921a 100644
--- a/src/main/java/de/cronn/testutils/ExecutorServiceExtension.java
+++ b/src/main/java/de/cronn/testutils/ExecutorServiceExtension.java
@@ -1,5 +1,6 @@
 package de.cronn.testutils;
 
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Callable;
@@ -15,17 +16,21 @@
 
 public class ExecutorServiceExtension implements BeforeEachCallback, AfterEachCallback {
 
-	private final long testTimeoutMillis;
+	private final Duration testTimeout;
 	private ExecutorService executorService;
 	private List<Future<?>> futures;
 
 	public ExecutorServiceExtension(long testTimeoutMillis) {
-		this.testTimeoutMillis = testTimeoutMillis;
+		this(Duration.ofMillis(testTimeoutMillis));
+	}
+
+	public ExecutorServiceExtension(Duration testTimeout) {
+		this.testTimeout = testTimeout;
 	}
 
 	@Override
 	public void afterEach(ExtensionContext context) {
-		ExecutorServiceUtils.shutdownOrThrow(executorService, getTestName(context), testTimeoutMillis);
+		ExecutorServiceUtils.shutdownOrThrow(executorService, getTestName(context), testTimeout);
 	}
 
 	@Override
@@ -62,7 +67,7 @@ public void awaitAllFutures() throws Exception {
 		}
 	}
 
-	class TestNameUtils {
+	static class TestNameUtils {
 
 		private TestNameUtils() {
 		}
diff --git a/src/main/java/de/cronn/testutils/ExecutorServiceUtils.java b/src/main/java/de/cronn/testutils/ExecutorServiceUtils.java
index 96a5d70..4ef7e88 100644
--- a/src/main/java/de/cronn/testutils/ExecutorServiceUtils.java
+++ b/src/main/java/de/cronn/testutils/ExecutorServiceUtils.java
@@ -1,5 +1,6 @@
 package de.cronn.testutils;
 
+import java.time.Duration;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.ThreadPoolExecutor;
@@ -16,11 +17,15 @@ public final class ExecutorServiceUtils {
 	private ExecutorServiceUtils() {
 	}
 
-	public static void shutdownOrThrow(ExecutorService executor, String executorServiceName, long timeoutMs) {
+	public static void shutdownOrThrow(ExecutorService executor, String executorServiceName, long timeoutMillis) {
+		shutdownOrThrow(executor, executorServiceName, Duration.ofMillis(timeoutMillis));
+	}
+
+	public static void shutdownOrThrow(ExecutorService executor, String executorServiceName, Duration timeout) {
 		if (executor != null) {
 			try {
-				if (!shutdownGracefully(executor, executorServiceName, timeoutMs)) {
-					boolean success = shutdownNow(executor, executorServiceName, timeoutMs);
+				if (!shutdownGracefully(executor, executorServiceName, timeout)) {
+					boolean success = shutdownNow(executor, executorServiceName, timeout);
 					Assertions.assertTrue(success, String.format("Failed to shutdown %s", executorServiceName));
 				}
 			} catch (InterruptedException e) {
@@ -31,11 +36,23 @@ public static void shutdownOrThrow(ExecutorService executor, String executorServ
 	}
 
 	public static boolean shutdownNow(ExecutorService executorService, String executorServiceName, long timeoutMillis) throws InterruptedException {
-		return shutdown(executorService, executorServiceName, timeoutMillis, true);
+		return shutdownNow(executorService, executorServiceName, Duration.ofMillis(timeoutMillis));
+	}
+
+	public static boolean shutdownNow(ExecutorService executorService, String executorServiceName, Duration timeout) throws InterruptedException {
+		return shutdown(executorService, executorServiceName, timeout, true);
 	}
 
 	public static boolean shutdownGracefully(ExecutorService executorService, String executorServiceName, long timeoutMillis) throws InterruptedException {
-		return shutdown(executorService, executorServiceName, timeoutMillis, false);
+		return shutdownGracefully(executorService, executorServiceName, Duration.ofMillis(timeoutMillis));
+	}
+
+	public static boolean shutdownGracefully(ExecutorService executorService, String executorServiceName, Duration timeout) throws InterruptedException {
+		return shutdown(executorService, executorServiceName, timeout, false);
+	}
+
+	private static boolean shutdown(ExecutorService executorService, String executorServiceName, Duration timeout, boolean shutdownWithInterrupt) throws InterruptedException {
+		return shutdown(executorService, executorServiceName, timeout.toMillis(), shutdownWithInterrupt);
 	}
 
 	private static boolean shutdown(ExecutorService executorService, String executorServiceName, long timeoutMillis, boolean shutdownWithInterrupt) throws InterruptedException {
@@ -53,8 +70,7 @@ private static boolean shutdown(ExecutorService executorService, String executor
 		if (success) {
 			log.info("Finished shutdown of '{}'", executorServiceName);
 		} else {
-			if (executorService instanceof ThreadPoolExecutor) {
-				ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService;
+			if (executorService instanceof ThreadPoolExecutor threadPoolExecutor) {
 				log.warn("Shutdown of '{}' timed out after {} ms. Active tasks: {}", executorServiceName, timeoutMillis, threadPoolExecutor.getActiveCount());
 			} else {
 				log.warn("Shutdown of '{}' timed out after {} ms.", executorServiceName, timeoutMillis);
@@ -64,8 +80,7 @@ private static boolean shutdown(ExecutorService executorService, String executor
 	}
 
 	private static void clearQueue(ExecutorService executorService, String executorServiceName) {
-		if (executorService instanceof ThreadPoolExecutor) {
-			ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService;
+		if (executorService instanceof ThreadPoolExecutor threadPoolExecutor) {
 			BlockingQueue<Runnable> queue = threadPoolExecutor.getQueue();
 			if (!queue.isEmpty()) {
 				int queueSize = queue.size();
diff --git a/src/main/java/de/cronn/testutils/spring/ResetClockExtension.java b/src/main/java/de/cronn/testutils/spring/ResetClockExtension.java
index 44d8779..e124d35 100644
--- a/src/main/java/de/cronn/testutils/spring/ResetClockExtension.java
+++ b/src/main/java/de/cronn/testutils/spring/ResetClockExtension.java
@@ -45,8 +45,8 @@ public static boolean hasDeclaredMethodOrder(ExtensionContext context) {
 	protected void resetClock(ExtensionContext context) {
 		ApplicationContext applicationContext = SpringExtension.getApplicationContext(context);
 		Clock clock = applicationContext.getBean(Clock.class);
-		if (clock instanceof TestClock) {
-			((TestClock) clock).reset();
+		if (clock instanceof TestClock testClock) {
+			testClock.reset();
 		}
 	}
 
diff --git a/src/test/java/de/cronn/testutils/ExecutorServiceExtensionTest.java b/src/test/java/de/cronn/testutils/ExecutorServiceExtensionTest.java
new file mode 100644
index 0000000..89f1e4b
--- /dev/null
+++ b/src/test/java/de/cronn/testutils/ExecutorServiceExtensionTest.java
@@ -0,0 +1,35 @@
+package de.cronn.testutils;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import java.time.Duration;
+import java.util.List;
+import java.util.concurrent.Future;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@ExtendWith(ThreadLeakCheck.class)
+class ExecutorServiceExtensionTest {
+
+    @RegisterExtension
+    ExecutorServiceExtension executorServiceExtension = new ExecutorServiceExtension(Duration.ofSeconds(10));
+
+    @Test
+    void testHappyCase() throws Exception {
+        executorServiceExtension.submit(() -> "one");
+        executorServiceExtension.submit(() -> "two");
+        executorServiceExtension.submit(() -> "three");
+
+        executorServiceExtension.awaitAllFutures();
+
+        List<Future<?>> futures = executorServiceExtension.getFutures();
+        assertThat(futures).hasSize(3);
+        assertThat(futures)
+                .map(Future::get)
+                .map(Object::toString)
+                .containsExactlyInAnyOrder("one", "two", "three");
+    }
+
+}