diff --git a/src/main/java/org/bitcoinj/core/AltcoinBlock.java b/src/main/java/org/bitcoinj/core/AltcoinBlock.java
index 6c506ba8..9620c9b6 100644
--- a/src/main/java/org/bitcoinj/core/AltcoinBlock.java
+++ b/src/main/java/org/bitcoinj/core/AltcoinBlock.java
@@ -60,14 +60,18 @@ public class AltcoinBlock extends org.bitcoinj.core.Block {
 
     private ScryptHash scryptHash;
 
-    /** Special case constructor, used for the genesis node, cloneAsHeader and unit tests. */
+    /** Special case constructor, used for the genesis node, cloneAsHeader and unit tests.
+     * @param params NetworkParameters object.
+     */
     public AltcoinBlock(final NetworkParameters params, final long version) {
         super(params, version);
     }
 
-    /** Special case constructor, used for the genesis node, cloneAsHeader and unit tests. */
-    public AltcoinBlock(NetworkParameters params, byte[] payloadBytes) {
-        this(params, payloadBytes, params.getDefaultSerializer(), payloadBytes.length);
+    /** Special case constructor, used for the genesis node, cloneAsHeader and unit tests.
+     * @param params NetworkParameters object.
+     */
+    public AltcoinBlock(final NetworkParameters params, final byte[] payloadBytes) {
+        this(params, payloadBytes, 0, params.getDefaultSerializer(), payloadBytes.length);
     }
 
     /**
@@ -78,9 +82,10 @@ public class AltcoinBlock extends org.bitcoinj.core.Block {
      * as the length will be provided as part of the header.  If unknown then set to Message.UNKNOWN_LENGTH
      * @throws ProtocolException
      */
-    public AltcoinBlock(NetworkParameters params, byte[] payloadBytes, MessageSerializer serializer, int length)
+    public AltcoinBlock(final NetworkParameters params, final byte[] payloadBytes,
+            final int offset, final MessageSerializer serializer, final int length)
             throws ProtocolException {
-        super(params, payloadBytes, serializer, length);
+        super(params, payloadBytes, offset, serializer, length);
     }
 
     public AltcoinBlock(NetworkParameters params, byte[] payloadBytes, int offset,
diff --git a/src/main/java/org/libdohj/core/AltcoinSerializer.java b/src/main/java/org/libdohj/core/AltcoinSerializer.java
index 42e4a905..1a00b4d3 100644
--- a/src/main/java/org/libdohj/core/AltcoinSerializer.java
+++ b/src/main/java/org/libdohj/core/AltcoinSerializer.java
@@ -22,12 +22,7 @@ public class AltcoinSerializer extends BitcoinSerializer {
     }
 
     @Override
-    public Block makeBlock(byte[] payloadBytes) throws ProtocolException {
-        return new AltcoinBlock(getParameters(), payloadBytes, this, payloadBytes.length);
-    }
-
-    @Override
-    public Block makeBlock(byte[] payloadBytes, int length) throws ProtocolException {
-        return new AltcoinBlock(getParameters(), payloadBytes, this, length);
+    public Block makeBlock(final byte[] payloadBytes, final int offset, final int length) throws ProtocolException {
+        return new AltcoinBlock(getParameters(), payloadBytes, offset, this, length);
     }
 }