diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/AcmeResource.java b/acme4j-client/src/main/java/org/shredzone/acme4j/AcmeResource.java
index c77fa320..4e01fae8 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/AcmeResource.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/AcmeResource.java
@@ -13,10 +13,9 @@
  */
 package org.shredzone.acme4j;
 
-import static org.shredzone.acme4j.util.AcmeUtils.assertNotNull;
-
 import java.io.Serializable;
 import java.net.URI;
+import java.util.Objects;
 
 /**
  * A generic ACME resource.
@@ -52,16 +51,14 @@ public abstract class AcmeResource implements Serializable {
      * Sets a new {@link Session}.
      */
     protected void setSession(Session session) {
-        assertNotNull(session, "session");
-        this.session = session;
+        this.session = Objects.requireNonNull(session, "session");
     }
 
     /**
      * Sets the resource's location.
      */
     protected void setLocation(URI location) {
-        assertNotNull(location, "location");
-        this.location = location;
+        this.location = Objects.requireNonNull(location, "location");
     }
 
     /**
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Registration.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Registration.java
index 7101f159..17efb7c6 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Registration.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Registration.java
@@ -28,6 +28,7 @@ import java.util.Date;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 import org.jose4j.jwk.PublicJsonWebKey;
 import org.jose4j.jws.JsonWebSignature;
@@ -38,7 +39,6 @@ import org.shredzone.acme4j.connector.ResourceIterator;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.exception.AcmeRetryAfterException;
-import org.shredzone.acme4j.util.AcmeUtils;
 import org.shredzone.acme4j.util.ClaimBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -177,7 +177,7 @@ public class Registration extends AcmeResource {
      * @return {@link Authorization} object for this domain
      */
     public Authorization authorizeDomain(String domain) throws AcmeException {
-        AcmeUtils.assertNotNull(domain, "domain");
+        Objects.requireNonNull(domain, "domain");
         if (domain.isEmpty()) {
             throw new IllegalArgumentException("domain must not be empty");
         }
@@ -231,7 +231,7 @@ public class Registration extends AcmeResource {
      */
     public Certificate requestCertificate(byte[] csr, Date notBefore, Date notAfter)
                 throws AcmeException {
-        AcmeUtils.assertNotNull(csr, "csr");
+        Objects.requireNonNull(csr, "csr");
 
         LOG.debug("requestCertificate");
         try (Connection conn = getSession().provider().connect()) {
@@ -269,7 +269,7 @@ public class Registration extends AcmeResource {
      *            new {@link KeyPair} to be used for identifying this account
      */
     public void changeKey(KeyPair newKeyPair) throws AcmeException {
-        AcmeUtils.assertNotNull(newKeyPair, "newKeyPair");
+        Objects.requireNonNull(newKeyPair, "newKeyPair");
         if (Arrays.equals(getSession().getKeyPair().getPrivate().getEncoded(),
                         newKeyPair.getPrivate().getEncoded())) {
             throw new IllegalArgumentException("newKeyPair must actually be a new key pair");
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Session.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Session.java
index a76fd6e1..e9bbcfdb 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Session.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Session.java
@@ -22,6 +22,7 @@ import java.util.EnumMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Objects;
 import java.util.ServiceLoader;
 
 import org.shredzone.acme4j.challenge.Challenge;
@@ -30,7 +31,6 @@ import org.shredzone.acme4j.connector.Resource;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.provider.AcmeProvider;
-import org.shredzone.acme4j.util.AcmeUtils;
 
 /**
  * A session stores the ACME server URI and the account's key pair. It also tracks
@@ -72,11 +72,8 @@ public class Session {
      *            {@link KeyPair} of the ACME account
      */
     public Session(URI serverUri, KeyPair keyPair) {
-        AcmeUtils.assertNotNull(serverUri, "serverUri");
-        AcmeUtils.assertNotNull(keyPair, "keyPair");
-
-        this.serverUri = serverUri;
-        this.keyPair = keyPair;
+        this.serverUri = Objects.requireNonNull(serverUri, "serverUri");
+        this.keyPair = Objects.requireNonNull(keyPair, "keyPair");
     }
 
     /**
@@ -166,7 +163,7 @@ public class Session {
      * @return {@link Challenge} instance
      */
     public Challenge createChallenge(Map<String, Object> data) {
-        AcmeUtils.assertNotNull(data, "data");
+        Objects.requireNonNull(data, "data");
 
         String type = (String) data.get("type");
         if (type == null || type.isEmpty()) {
@@ -194,9 +191,8 @@ public class Session {
      * @return {@link URI}, or {@code null} if the server does not offer that resource
      */
     public URI resourceUri(Resource resource) throws AcmeException {
-        AcmeUtils.assertNotNull(resource, "resource");
         readDirectory();
-        return resourceMap.get(resource);
+        return resourceMap.get(Objects.requireNonNull(resource, "resource"));
     }
 
     /**
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/Challenge.java b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/Challenge.java
index 618c39ff..be56b563 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/Challenge.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/Challenge.java
@@ -25,6 +25,7 @@ import java.net.URL;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 import org.jose4j.json.JsonUtil;
 import org.jose4j.lang.JoseException;
@@ -35,7 +36,6 @@ import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.exception.AcmeRetryAfterException;
-import org.shredzone.acme4j.util.AcmeUtils;
 import org.shredzone.acme4j.util.ClaimBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -71,8 +71,8 @@ public class Challenge extends AcmeResource {
      */
     @SuppressWarnings("unchecked")
     public static <T extends Challenge> T bind(Session session, URI location) throws AcmeException {
-        AcmeUtils.assertNotNull(session, "session");
-        AcmeUtils.assertNotNull(location, "location");
+        Objects.requireNonNull(session, "session");
+        Objects.requireNonNull(location, "location");
 
         LOG.debug("bind");
         try (Connection conn = session.provider().connect()) {
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java
index 20dc2862..d6364dfe 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java
@@ -34,6 +34,7 @@ import java.util.Collection;
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -51,7 +52,6 @@ import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.exception.AcmeRateLimitExceededException;
 import org.shredzone.acme4j.exception.AcmeServerException;
 import org.shredzone.acme4j.exception.AcmeUnauthorizedException;
-import org.shredzone.acme4j.util.AcmeUtils;
 import org.shredzone.acme4j.util.ClaimBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -73,14 +73,13 @@ public class DefaultConnection implements Connection {
     protected HttpURLConnection conn;
 
     public DefaultConnection(HttpConnector httpConnector) {
-        AcmeUtils.assertNotNull(httpConnector, "httpConnector");
-        this.httpConnector = httpConnector;
+        this.httpConnector = Objects.requireNonNull(httpConnector, "httpConnector");
     }
 
     @Override
     public void sendRequest(URI uri, Session session) throws AcmeException {
-        AcmeUtils.assertNotNull(uri, "uri");
-        AcmeUtils.assertNotNull(session, "session");
+        Objects.requireNonNull(uri, "uri");
+        Objects.requireNonNull(session, "session");
         assertConnectionIsClosed();
 
         LOG.debug("GET {}", uri);
@@ -102,9 +101,9 @@ public class DefaultConnection implements Connection {
 
     @Override
     public void sendSignedRequest(URI uri, ClaimBuilder claims, Session session) throws AcmeException {
-        AcmeUtils.assertNotNull(uri, "uri");
-        AcmeUtils.assertNotNull(claims, "claims");
-        AcmeUtils.assertNotNull(session, "session");
+        Objects.requireNonNull(uri, "uri");
+        Objects.requireNonNull(claims, "claims");
+        Objects.requireNonNull(session, "session");
         assertConnectionIsClosed();
 
         try {
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/exception/AcmeServerException.java b/acme4j-client/src/main/java/org/shredzone/acme4j/exception/AcmeServerException.java
index b4cc5e41..4e961064 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/exception/AcmeServerException.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/exception/AcmeServerException.java
@@ -13,8 +13,9 @@
  */
 package org.shredzone.acme4j.exception;
 
+import java.util.Objects;
+
 import org.shredzone.acme4j.connector.DefaultConnection;
-import org.shredzone.acme4j.util.AcmeUtils;
 
 /**
  * An exception that is thrown when the ACME server returned an error. It contains
@@ -36,8 +37,7 @@ public class AcmeServerException extends AcmeException {
      */
     public AcmeServerException(String type, String detail) {
         super(detail);
-        AcmeUtils.assertNotNull(type, "type");
-        this.type = type;
+        this.type = Objects.requireNonNull(type, "type");
     }
 
     /**
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/provider/AbstractAcmeProvider.java b/acme4j-client/src/main/java/org/shredzone/acme4j/provider/AbstractAcmeProvider.java
index a122c239..faa2e11b 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/provider/AbstractAcmeProvider.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/provider/AbstractAcmeProvider.java
@@ -16,6 +16,7 @@ package org.shredzone.acme4j.provider;
 import java.net.HttpURLConnection;
 import java.net.URI;
 import java.util.Map;
+import java.util.Objects;
 
 import org.shredzone.acme4j.Session;
 import org.shredzone.acme4j.challenge.Challenge;
@@ -27,7 +28,6 @@ import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.connector.DefaultConnection;
 import org.shredzone.acme4j.connector.HttpConnector;
 import org.shredzone.acme4j.exception.AcmeException;
-import org.shredzone.acme4j.util.AcmeUtils;
 
 /**
  * Abstract implementation of {@link AcmeProvider}. It consists of a challenge
@@ -59,8 +59,8 @@ public abstract class AbstractAcmeProvider implements AcmeProvider {
     @Override
     @SuppressWarnings("deprecation") // must still provide deprecated challenges
     public Challenge createChallenge(Session session, String type) {
-        AcmeUtils.assertNotNull(session, "session");
-        AcmeUtils.assertNotNull(type, "type");
+        Objects.requireNonNull(session, "session");
+        Objects.requireNonNull(type, "type");
         if (type.isEmpty()) {
             throw new IllegalArgumentException("no type given");
         }
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/util/AcmeUtils.java b/acme4j-client/src/main/java/org/shredzone/acme4j/util/AcmeUtils.java
index 9ddf54f8..557b53ec 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/util/AcmeUtils.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/util/AcmeUtils.java
@@ -99,21 +99,6 @@ public final class AcmeUtils {
         return Base64Url.encode(data);
     }
 
-    /**
-     * Asserts that the given value is not {@code null}. Otherwise a
-     * {@link NullPointerException} is thrown.
-     *
-     * @param value
-     *            Value to test
-     * @param name
-     *            Name of the parameter
-     */
-    public static void assertNotNull(Object value, String name) {
-        if (value == null) {
-            throw new NullPointerException(name + " must not be null");
-        }
-    }
-
     /**
      * ASCII encodes a domain name.
      * <p>
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/util/ClaimBuilder.java b/acme4j-client/src/main/java/org/shredzone/acme4j/util/ClaimBuilder.java
index 8d63cf44..f554e79b 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/util/ClaimBuilder.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/util/ClaimBuilder.java
@@ -21,6 +21,7 @@ import java.text.SimpleDateFormat;
 import java.util.Collections;
 import java.util.Date;
 import java.util.Map;
+import java.util.Objects;
 import java.util.TimeZone;
 import java.util.TreeMap;
 
@@ -56,8 +57,7 @@ public class ClaimBuilder {
      * @return {@code this}
      */
     public ClaimBuilder put(String key, Object value) {
-        AcmeUtils.assertNotNull(key, "key");
-        data.put(key, value);
+        data.put(Objects.requireNonNull(key, "key"), value);
         return this;
     }
 
@@ -141,7 +141,7 @@ public class ClaimBuilder {
      * @return {@code this}
      */
     public ClaimBuilder putKey(String key, PublicKey publickey) {
-        AcmeUtils.assertNotNull(publickey, "publickey");
+        Objects.requireNonNull(publickey, "publickey");
 
         try {
             final PublicJsonWebKey jwk = PublicJsonWebKey.Factory.newPublicJwk(publickey);
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/util/AcmeUtilsTest.java b/acme4j-client/src/test/java/org/shredzone/acme4j/util/AcmeUtilsTest.java
index 60313656..603796e7 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/util/AcmeUtilsTest.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/util/AcmeUtilsTest.java
@@ -85,21 +85,6 @@ public class AcmeUtilsTest {
         assertThat(base64UrlEncode, is("w6uP8Tcg6K2QR905Rms8iXTlksL6OD1KOWBxTK7wxPI"));
     }
 
-    /**
-     * Test that {@code null} check works properly.
-     */
-    @Test
-    public void testAssertNotNull() {
-        AcmeUtils.assertNotNull(new Object(), "foo");
-
-        try {
-            AcmeUtils.assertNotNull(null, "bar");
-            fail("null was accepted");
-        } catch (NullPointerException ex) {
-            // expected
-        }
-    }
-
     /**
      * Test ACE conversion.
      */
diff --git a/acme4j-utils/src/main/java/org/shredzone/acme4j/util/CSRBuilder.java b/acme4j-utils/src/main/java/org/shredzone/acme4j/util/CSRBuilder.java
index 49daf9de..6849681d 100644
--- a/acme4j-utils/src/main/java/org/shredzone/acme4j/util/CSRBuilder.java
+++ b/acme4j-utils/src/main/java/org/shredzone/acme4j/util/CSRBuilder.java
@@ -25,6 +25,7 @@ import java.security.interfaces.ECKey;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Objects;
 
 import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
 import org.bouncycastle.asn1.x500.X500Name;
@@ -147,7 +148,7 @@ public class CSRBuilder {
      *            {@link KeyPair} to sign the CSR with
      */
     public void sign(KeyPair keypair) throws IOException {
-        AcmeUtils.assertNotNull(keypair, "keypair");
+        Objects.requireNonNull(keypair, "keypair");
         if (namelist.isEmpty()) {
             throw new IllegalStateException("No domain was set");
         }