diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Identifier.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Identifier.java
index 16e7d479..d02a0cef 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Identifier.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Identifier.java
@@ -46,14 +46,14 @@ public class Identifier implements Serializable {
     /**
      * Type constant for DNS identifiers.
      */
-    public static final String DNS = "dns";
+    public static final String TYPE_DNS = "dns";
 
     /**
      * Type constant for IP identifiers.
      *
      * @see <a href="https://tools.ietf.org/html/draft-ietf-acme-ip">draft-ietf-acme-ip</a>
      */
-    public static final String IP = "ip";
+    public static final String TYPE_IP = "ip";
 
     private static final String KEY_TYPE = "type";
     private static final String KEY_VALUE = "value";
@@ -61,28 +61,6 @@ public class Identifier implements Serializable {
     private final String type;
     private final String value;
 
-    /**
-     * Creates a new DNS identifier for the given domain name.
-     *
-     * @param domain
-     *            Domain name. Unicode domains are automatically ASCII encoded.
-     * @return New {@link Identifier}
-     */
-    public static Identifier dns(String domain) {
-        return new Identifier(DNS, toAce(domain));
-    }
-
-    /**
-     * Creates a new IP identifier for the given {@link InetAddress}.
-     *
-     * @param ip
-     *            {@link InetAddress}
-     * @return New {@link Identifier}
-     */
-    public static Identifier ip(InetAddress ip) {
-        return new Identifier(IP, ip.getHostAddress());
-    }
-
     /**
      * Creates a new {@link Identifier}.
      * <p>
@@ -112,6 +90,28 @@ public class Identifier implements Serializable {
         this(json.get(KEY_TYPE).asString(), json.get(KEY_VALUE).asString());
     }
 
+    /**
+     * Creates a new DNS identifier for the given domain name.
+     *
+     * @param domain
+     *            Domain name. Unicode domains are automatically ASCII encoded.
+     * @return New {@link Identifier}
+     */
+    public static Identifier dns(String domain) {
+        return new Identifier(TYPE_DNS, toAce(domain));
+    }
+
+    /**
+     * Creates a new IP identifier for the given {@link InetAddress}.
+     *
+     * @param ip
+     *            {@link InetAddress}
+     * @return New {@link Identifier}
+     */
+    public static Identifier ip(InetAddress ip) {
+        return new Identifier(TYPE_IP, ip.getHostAddress());
+    }
+
     /**
      * Returns the identifier type.
      */
@@ -134,7 +134,7 @@ public class Identifier implements Serializable {
      *             if this is not a DNS identifier.
      */
     public String getDomain() {
-        if (!DNS.equals(type)) {
+        if (!TYPE_DNS.equals(type)) {
             throw new AcmeProtocolException("expected 'dns' identifier, but found '" + type + "'");
         }
         return value;
@@ -148,7 +148,7 @@ public class Identifier implements Serializable {
      *             if this is not a DNS identifier.
      */
     public InetAddress getIP() {
-        if (!IP.equals(type)) {
+        if (!TYPE_IP.equals(type)) {
             throw new AcmeProtocolException("expected 'ip' identifier, but found '" + type + "'");
         }
         try {
@@ -183,6 +183,6 @@ public class Identifier implements Serializable {
     @Override
     public int hashCode() {
         return type.hashCode() ^ value.hashCode();
-    };
+    }
 
 }
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Order.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Order.java
index e82d348c..35452e1d 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Order.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Order.java
@@ -77,7 +77,7 @@ public class Order extends AcmeJsonResource {
     @Deprecated
     public List<String> getDomains() {
         return getIdentifiers().stream()
-                    .filter(i -> Identifier.DNS.equals(i.getType()))
+                    .filter(i -> Identifier.TYPE_DNS.equals(i.getType()))
                     .map(Identifier::getDomain)
                     .collect(toList());
     }
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/IdentifierTest.java b/acme4j-client/src/test/java/org/shredzone/acme4j/IdentifierTest.java
index 3aa90981..3cab9375 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/IdentifierTest.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/IdentifierTest.java
@@ -31,8 +31,8 @@ public class IdentifierTest {
 
     @Test
     public void testConstants() {
-        assertThat(Identifier.DNS, is("dns"));
-        assertThat(Identifier.IP, is("ip"));
+        assertThat(Identifier.TYPE_DNS, is("dns"));
+        assertThat(Identifier.TYPE_IP, is("ip"));
     }
 
     @Test
@@ -62,12 +62,12 @@ public class IdentifierTest {
     @Test
     public void testDns() {
         Identifier id1 = Identifier.dns("example.com");
-        assertThat(id1.getType(), is(Identifier.DNS));
+        assertThat(id1.getType(), is(Identifier.TYPE_DNS));
         assertThat(id1.getValue(), is("example.com"));
         assertThat(id1.getDomain(), is("example.com"));
 
         Identifier id2 = Identifier.dns("ëxämþlë.com");
-        assertThat(id2.getType(), is(Identifier.DNS));
+        assertThat(id2.getType(), is(Identifier.TYPE_DNS));
         assertThat(id2.getValue(), is("xn--xml-qla7ae5k.com"));
         assertThat(id2.getDomain(), is("xn--xml-qla7ae5k.com"));
     }
@@ -80,12 +80,12 @@ public class IdentifierTest {
     @Test
     public void testIp() throws UnknownHostException {
         Identifier id1 = Identifier.ip(InetAddress.getByName("192.168.1.2"));
-        assertThat(id1.getType(), is(Identifier.IP));
+        assertThat(id1.getType(), is(Identifier.TYPE_IP));
         assertThat(id1.getValue(), is("192.168.1.2"));
         assertThat(id1.getIP().getHostAddress(), is("192.168.1.2"));
 
         Identifier id2 = Identifier.ip(InetAddress.getByName("2001:db8:85a3::8a2e:370:7334"));
-        assertThat(id2.getType(), is(Identifier.IP));
+        assertThat(id2.getType(), is(Identifier.TYPE_IP));
         assertThat(id2.getValue(), is("2001:db8:85a3:0:0:8a2e:370:7334"));
         assertThat(id2.getIP().getHostAddress(), is("2001:db8:85a3:0:0:8a2e:370:7334"));
     }