diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/DnsChallenge.java b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/DnsChallenge.java
index ea9590df..b3db9601 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/DnsChallenge.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/DnsChallenge.java
@@ -29,7 +29,7 @@ import org.shredzone.acme4j.util.ClaimBuilder;
 public class DnsChallenge extends GenericChallenge {
 
     /**
-     * Challenge type name.
+     * Challenge type name: {@value}
      */
     public static final String TYPE = "dns-01";
 
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/HttpChallenge.java b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/HttpChallenge.java
index 8b8f7e26..33201acf 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/HttpChallenge.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/HttpChallenge.java
@@ -25,7 +25,7 @@ import org.shredzone.acme4j.util.ClaimBuilder;
 public class HttpChallenge extends GenericChallenge {
 
     /**
-     * Challenge type name.
+     * Challenge type name: {@value}
      */
     public static final String TYPE = "http-01";
 
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/ProofOfPossessionChallenge.java b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/ProofOfPossessionChallenge.java
index 59050ac7..a3e9da20 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/ProofOfPossessionChallenge.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/ProofOfPossessionChallenge.java
@@ -28,7 +28,7 @@ import org.shredzone.acme4j.util.ClaimBuilder;
 public class ProofOfPossessionChallenge extends GenericChallenge {
 
     /**
-     * Challenge type name.
+     * Challenge type name: {@value}
      */
     public static final String TYPE = "proofOfPossession-01";
 
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/TlsSniChallenge.java b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/TlsSniChallenge.java
index fee9080e..a6acc9a2 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/TlsSniChallenge.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/challenge/TlsSniChallenge.java
@@ -23,7 +23,7 @@ package org.shredzone.acme4j.challenge;
 public class TlsSniChallenge extends GenericChallenge {
 
     /**
-     * Challenge type name.
+     * Challenge type name: {@value}
      */
     public static final String TYPE = "tls-sni-01";