diff --git a/wire/blockheader.go b/wire/blockheader.go
index 99199197e..183c7e1c4 100644
--- a/wire/blockheader.go
+++ b/wire/blockheader.go
@@ -18,7 +18,7 @@ import (
 // + NumPrevBlocks 1 byte + MerkleRoot hash.
 // To get total size of block header len(PrevBlocks) * chainhash.HashSize should be
 // added to this value
-const BaseBlockHeaderPayload = 21 + (chainhash.HashSize)
+const BaseBlockHeaderPayload = 17 + (chainhash.HashSize)
 
 // MaxNumPrevBlocks is the maximum number of previous blocks a block can reference.
 // Currently set to 255 as the maximum number NumPrevBlocks can be due to it being a byte
@@ -29,7 +29,7 @@ const MaxNumPrevBlocks = 255
 const MaxBlockHeaderPayload = BaseBlockHeaderPayload + (MaxNumPrevBlocks * chainhash.HashSize)
 
 // BlockHeader defines information about a block and is used in the bitcoin
-// block (MsgBlock) and headers (MsgHeader ) messages.
+// block (MsgBlock) and headers (MsgHeader) messages.
 type BlockHeader struct {
 	// Version of the block.  This is not the same as the protocol version.
 	Version int32
@@ -54,10 +54,6 @@ type BlockHeader struct {
 	Nonce uint32
 }
 
-// blockHeaderLen is a constant that represents the number of bytes for a block
-// header.
-const blockHeaderLen = 80
-
 // BlockHash computes the block identifier hash for the given block header.
 func (h *BlockHeader) BlockHash() chainhash.Hash {
 	// Encode the header and double sha256 everything prior to the number of
@@ -106,6 +102,12 @@ func (h *BlockHeader) Serialize(w io.Writer) error {
 	return writeBlockHeader(w, 0, h)
 }
 
+// SerializeSize returns the number of bytes it would take to serialize the
+// block header.
+func (h *BlockHeader) SerializeSize() int {
+	return BaseBlockHeaderPayload + int(h.NumPrevBlocks)*chainhash.HashSize
+}
+
 // NewBlockHeader returns a new BlockHeader using the provided version, previous
 // block hash, merkle root hash, difficulty bits, and nonce used to generate the
 // block with defaults or calclulated values for the remaining fields.
@@ -134,13 +136,12 @@ func readBlockHeader(r io.Reader, pver uint32, bh *BlockHeader) error {
 		return err
 	}
 
-	bh.NumPrevBlocks, err = binarySerializer.Uint8(r)
-	if err != nil {
-		return err
-	}
 	bh.PrevBlocks = make([]chainhash.Hash, bh.NumPrevBlocks)
 	for i := byte(0); i < bh.NumPrevBlocks; i++ {
-		readElement(r, &bh.PrevBlocks[i])
+		err := readElement(r, &bh.PrevBlocks[i])
+		if err != nil {
+			return err
+		}
 	}
 	return readElements(r, &bh.MerkleRoot, (*uint32Time)(&bh.Timestamp), &bh.Bits, &bh.Nonce)
 }
diff --git a/wire/blockheader_test.go b/wire/blockheader_test.go
index 2035b1aa7..5c51d1a64 100644
--- a/wire/blockheader_test.go
+++ b/wire/blockheader_test.go
@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/daglabs/btcd/chaincfg/chainhash"
 	"github.com/davecgh/go-spew/spew"
 )
 
@@ -21,15 +22,16 @@ func TestBlockHeader(t *testing.T) {
 	}
 	nonce := uint32(nonce64)
 
-	hash := mainNetGenesisHash
+	hashes := []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash}
+
 	merkleHash := mainNetGenesisMerkleRoot
 	bits := uint32(0x1d00ffff)
-	bh := NewBlockHeader(1, &hash, &merkleHash, bits, nonce)
+	bh := NewBlockHeader(1, hashes, &merkleHash, bits, nonce)
 
 	// Ensure we get the same data back out.
-	if !bh.PrevBlock.IsEqual(&hash) {
-		t.Errorf("NewBlockHeader: wrong prev hash - got %v, want %v",
-			spew.Sprint(bh.PrevBlock), spew.Sprint(hash))
+	if !reflect.DeepEqual(bh.PrevBlocks, hashes) {
+		t.Errorf("NewBlockHeader: wrong prev hashes - got %v, want %v",
+			spew.Sprint(bh.PrevBlocks), spew.Sprint(hashes))
 	}
 	if !bh.MerkleRoot.IsEqual(&merkleHash) {
 		t.Errorf("NewBlockHeader: wrong merkle root - got %v, want %v",
@@ -54,25 +56,31 @@ func TestBlockHeaderWire(t *testing.T) {
 	// baseBlockHdr is used in the various tests as a baseline BlockHeader.
 	bits := uint32(0x1d00ffff)
 	baseBlockHdr := &BlockHeader{
-		Version:    1,
-		PrevBlock:  mainNetGenesisHash,
-		MerkleRoot: mainNetGenesisMerkleRoot,
-		Timestamp:  time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
-		Bits:       bits,
-		Nonce:      nonce,
+		Version:       1,
+		NumPrevBlocks: 2,
+		PrevBlocks:    []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		MerkleRoot:    mainNetGenesisMerkleRoot,
+		Timestamp:     time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
+		Bits:          bits,
+		Nonce:         nonce,
 	}
 
 	// baseBlockHdrEncoded is the wire encoded bytes of baseBlockHdr.
 	baseBlockHdrEncoded := []byte{
 		0x01, 0x00, 0x00, 0x00, // Version 1
-		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+		0x02,                                           // NumPrevBlocks
+		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 		0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 		0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2,
+		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+		0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+		0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+		0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
 		0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
 		0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
-		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a, // MerkleRoot
+		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 		0x29, 0xab, 0x5f, 0x49, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0xf3, 0xe0, 0x01, 0x00, // Nonce
@@ -187,25 +195,31 @@ func TestBlockHeaderSerialize(t *testing.T) {
 	// baseBlockHdr is used in the various tests as a baseline BlockHeader.
 	bits := uint32(0x1d00ffff)
 	baseBlockHdr := &BlockHeader{
-		Version:    1,
-		PrevBlock:  mainNetGenesisHash,
-		MerkleRoot: mainNetGenesisMerkleRoot,
-		Timestamp:  time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
-		Bits:       bits,
-		Nonce:      nonce,
+		Version:       1,
+		NumPrevBlocks: 2,
+		PrevBlocks:    []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		MerkleRoot:    mainNetGenesisMerkleRoot,
+		Timestamp:     time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
+		Bits:          bits,
+		Nonce:         nonce,
 	}
 
 	// baseBlockHdrEncoded is the wire encoded bytes of baseBlockHdr.
 	baseBlockHdrEncoded := []byte{
 		0x01, 0x00, 0x00, 0x00, // Version 1
-		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+		0x02,                                           // NumPrevBlocks
+		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 		0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 		0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2,
+		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+		0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+		0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+		0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
 		0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
 		0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
-		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a, // MerkleRoot
+		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 		0x29, 0xab, 0x5f, 0x49, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0xf3, 0xe0, 0x01, 0x00, // Nonce
@@ -253,3 +267,51 @@ func TestBlockHeaderSerialize(t *testing.T) {
 		}
 	}
 }
+
+// TestBlockHeaderSerializeSize performs tests to ensure the serialize size for
+// various block headers is accurate.
+func TestBlockHeaderSerializeSize(t *testing.T) {
+	nonce := uint32(123123) // 0x1e0f3
+	bits := uint32(0x1d00ffff)
+	timestamp := time.Unix(0x495fab29, 0) // 2009-01-03 12:15:05 -0600 CST
+	baseBlockHdr := &BlockHeader{
+		Version:       1,
+		NumPrevBlocks: 2,
+		PrevBlocks:    []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		MerkleRoot:    mainNetGenesisMerkleRoot,
+		Timestamp:     timestamp,
+		Bits:          bits,
+		Nonce:         nonce,
+	}
+
+	genesisBlockHdr := &BlockHeader{
+		Version:       1,
+		NumPrevBlocks: 0,
+		PrevBlocks:    []chainhash.Hash{},
+		MerkleRoot:    mainNetGenesisMerkleRoot,
+		Timestamp:     timestamp,
+		Bits:          bits,
+		Nonce:         nonce,
+	}
+	tests := []struct {
+		in   *BlockHeader // Block header to encode
+		size int          // Expected serialized size
+	}{
+		// Block with no transactions.
+		{genesisBlockHdr, 49},
+
+		// First block in the mainnet block chain.
+		{baseBlockHdr, 113},
+	}
+
+	t.Logf("Running %d tests", len(tests))
+	for i, test := range tests {
+		serializedSize := test.in.SerializeSize()
+		if serializedSize != test.size {
+			t.Errorf("BlockHeader.SerializeSize: #%d got: %d, want: "+
+				"%d", i, serializedSize, test.size)
+
+			continue
+		}
+	}
+}
diff --git a/wire/common_test.go b/wire/common_test.go
index afd81665f..279221b94 100644
--- a/wire/common_test.go
+++ b/wire/common_test.go
@@ -25,6 +25,15 @@ var mainNetGenesisHash = chainhash.Hash([chainhash.HashSize]byte{ // Make go vet
 	0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
 })
 
+// simNetGenesisHash is the hash of the first block in the block chain for the
+// simulation test network.
+var simNetGenesisHash = chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
+	0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a,
+	0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+	0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+	0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+})
+
 // mainNetGenesisMerkleRoot is the hash of the first transaction in the genesis
 // block for the main network.
 var mainNetGenesisMerkleRoot = chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
diff --git a/wire/message_test.go b/wire/message_test.go
index d38fd0e34..c745b8f66 100644
--- a/wire/message_test.go
+++ b/wire/message_test.go
@@ -66,7 +66,7 @@ func TestMessage(t *testing.T) {
 	msgFilterAdd := NewMsgFilterAdd([]byte{0x01})
 	msgFilterClear := NewMsgFilterClear()
 	msgFilterLoad := NewMsgFilterLoad([]byte{0x01}, 10, 0, BloomUpdateNone)
-	bh := NewBlockHeader(1, &chainhash.Hash{}, &chainhash.Hash{}, 0, 0)
+	bh := NewBlockHeader(1, []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash}, &chainhash.Hash{}, 0, 0)
 	msgMerkleBlock := NewMsgMerkleBlock(bh)
 	msgReject := NewMsgReject("block", RejectDuplicate, "duplicate block")
 	msgGetCFilters := NewMsgGetCFilters(GCSFilterExtended, 0, &chainhash.Hash{})
@@ -89,7 +89,7 @@ func TestMessage(t *testing.T) {
 		{msgGetAddr, msgGetAddr, pver, MainNet, 24},
 		{msgAddr, msgAddr, pver, MainNet, 25},
 		{msgGetBlocks, msgGetBlocks, pver, MainNet, 61},
-		{msgBlock, msgBlock, pver, MainNet, 239},
+		{msgBlock, msgBlock, pver, MainNet, 272},
 		{msgInv, msgInv, pver, MainNet, 25},
 		{msgGetData, msgGetData, pver, MainNet, 25},
 		{msgNotFound, msgNotFound, pver, MainNet, 25},
@@ -103,7 +103,7 @@ func TestMessage(t *testing.T) {
 		{msgFilterAdd, msgFilterAdd, pver, MainNet, 26},
 		{msgFilterClear, msgFilterClear, pver, MainNet, 24},
 		{msgFilterLoad, msgFilterLoad, pver, MainNet, 35},
-		{msgMerkleBlock, msgMerkleBlock, pver, MainNet, 110},
+		{msgMerkleBlock, msgMerkleBlock, pver, MainNet, 143},
 		{msgReject, msgReject, pver, MainNet, 79},
 		{msgGetCFilters, msgGetCFilters, pver, MainNet, 61},
 		{msgGetCFHeaders, msgGetCFHeaders, pver, MainNet, 61},
diff --git a/wire/msgblock.go b/wire/msgblock.go
index d94e6313d..dd4409a94 100644
--- a/wire/msgblock.go
+++ b/wire/msgblock.go
@@ -202,7 +202,7 @@ func (msg *MsgBlock) Serialize(w io.Writer) error {
 func (msg *MsgBlock) SerializeSize() int {
 	// Block header bytes + Serialized varint size for the number of
 	// transactions.
-	n := blockHeaderLen + VarIntSerializeSize(uint64(len(msg.Transactions)))
+	n := msg.Header.SerializeSize() + VarIntSerializeSize(uint64(len(msg.Transactions)))
 
 	for _, tx := range msg.Transactions {
 		n += tx.SerializeSize()
diff --git a/wire/msgblock_test.go b/wire/msgblock_test.go
index 2ff6351b3..406e3ff79 100644
--- a/wire/msgblock_test.go
+++ b/wire/msgblock_test.go
@@ -20,11 +20,11 @@ func TestBlock(t *testing.T) {
 	pver := ProtocolVersion
 
 	// Block 1 header.
-	prevHash := &blockOne.Header.PrevBlock
+	prevHashes := blockOne.Header.PrevBlocks
 	merkleHash := &blockOne.Header.MerkleRoot
 	bits := blockOne.Header.Bits
 	nonce := blockOne.Header.Nonce
-	bh := NewBlockHeader(1, prevHash, merkleHash, bits, nonce)
+	bh := NewBlockHeader(1, prevHashes, merkleHash, bits, nonce)
 
 	// Ensure the command is expected value.
 	wantCmd := "block"
@@ -92,7 +92,7 @@ func TestBlockTxHashes(t *testing.T) {
 // TestBlockHash tests the ability to generate the hash of a block accurately.
 func TestBlockHash(t *testing.T) {
 	// Block 1 hash.
-	hashStr := "839a8e6886ab5951d76f411475428afc90947ee320161bbf18eb6048"
+	hashStr := "2357979742c556c68e90bf624a1139af8c85cafb4ac98d6d1dc367cd661ef67d"
 	wantHash, err := chainhash.NewHashFromStr(hashStr)
 	if err != nil {
 		t.Errorf("NewHashFromStr: %v", err)
@@ -211,20 +211,24 @@ func TestBlockWireErrors(t *testing.T) {
 	}{
 		// Force error in version.
 		{&blockOne, blockOneBytes, pver, 0, io.ErrShortWrite, io.EOF},
-		// Force error in prev block hash.
+		// Force error in num block hashes.
 		{&blockOne, blockOneBytes, pver, 4, io.ErrShortWrite, io.EOF},
+		// Force error in prev block hash #1.
+		{&blockOne, blockOneBytes, pver, 5, io.ErrShortWrite, io.EOF},
+		// Force error in prev block hash #2.
+		{&blockOne, blockOneBytes, pver, 37, io.ErrShortWrite, io.EOF},
 		// Force error in merkle root.
-		{&blockOne, blockOneBytes, pver, 36, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 69, io.ErrShortWrite, io.EOF},
 		// Force error in timestamp.
-		{&blockOne, blockOneBytes, pver, 68, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 101, io.ErrShortWrite, io.EOF},
 		// Force error in difficulty bits.
-		{&blockOne, blockOneBytes, pver, 72, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 105, io.ErrShortWrite, io.EOF},
 		// Force error in header nonce.
-		{&blockOne, blockOneBytes, pver, 76, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 109, io.ErrShortWrite, io.EOF},
 		// Force error in transaction count.
-		{&blockOne, blockOneBytes, pver, 80, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 113, io.ErrShortWrite, io.EOF},
 		// Force error in transactions.
-		{&blockOne, blockOneBytes, pver, 81, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 114, io.ErrShortWrite, io.EOF},
 	}
 
 	t.Logf("Running %d tests", len(tests))
@@ -329,20 +333,24 @@ func TestBlockSerializeErrors(t *testing.T) {
 	}{
 		// Force error in version.
 		{&blockOne, blockOneBytes, 0, io.ErrShortWrite, io.EOF},
-		// Force error in prev block hash.
+		// Force error in numPrevBlocks.
 		{&blockOne, blockOneBytes, 4, io.ErrShortWrite, io.EOF},
+		// Force error in prev block hash #1.
+		{&blockOne, blockOneBytes, 5, io.ErrShortWrite, io.EOF},
+		// Force error in prev block hash #2.
+		{&blockOne, blockOneBytes, 37, io.ErrShortWrite, io.EOF},
 		// Force error in merkle root.
-		{&blockOne, blockOneBytes, 36, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 69, io.ErrShortWrite, io.EOF},
 		// Force error in timestamp.
-		{&blockOne, blockOneBytes, 68, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 101, io.ErrShortWrite, io.EOF},
 		// Force error in difficulty bits.
-		{&blockOne, blockOneBytes, 72, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 105, io.ErrShortWrite, io.EOF},
 		// Force error in header nonce.
-		{&blockOne, blockOneBytes, 76, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 109, io.ErrShortWrite, io.EOF},
 		// Force error in transaction count.
-		{&blockOne, blockOneBytes, 80, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 113, io.ErrShortWrite, io.EOF},
 		// Force error in transactions.
-		{&blockOne, blockOneBytes, 81, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 114, io.ErrShortWrite, io.EOF},
 	}
 
 	t.Logf("Running %d tests", len(tests))
@@ -396,14 +404,19 @@ func TestBlockOverflowErrors(t *testing.T) {
 		{
 			[]byte{
 				0x01, 0x00, 0x00, 0x00, // Version 1
-				0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+				0x02,                                           // NumPrevBlocks
+				0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 				0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 				0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-				0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-				0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
-				0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
-				0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-				0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e, // MerkleRoot
+				0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+				0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+				0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+				0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+				0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
+				0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
+				0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
+				0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 				0x61, 0xbc, 0x66, 0x49, // Timestamp
 				0xff, 0xff, 0x00, 0x1d, // Bits
 				0x01, 0xe3, 0x62, 0x99, // Nonce
@@ -456,7 +469,7 @@ func TestBlockSerializeSize(t *testing.T) {
 		size int       // Expected serialized size
 	}{
 		// Block with no transactions.
-		{noTxBlock, 81},
+		{noTxBlock, 114},
 
 		// First block in the mainnet block chain.
 		{&blockOne, len(blockOneBytes)},
@@ -468,6 +481,7 @@ func TestBlockSerializeSize(t *testing.T) {
 		if serializedSize != test.size {
 			t.Errorf("MsgBlock.SerializeSize: #%d got: %d, want: "+
 				"%d", i, serializedSize, test.size)
+
 			continue
 		}
 	}
@@ -476,19 +490,10 @@ func TestBlockSerializeSize(t *testing.T) {
 // blockOne is the first block in the mainnet block chain.
 var blockOne = MsgBlock{
 	Header: BlockHeader{
-		Version: 1,
-		PrevBlock: chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
-			0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
-			0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
-			0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-			0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
-		}),
-		MerkleRoot: chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
-			0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
-			0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
-			0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-			0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e,
-		}),
+		Version:       1,
+		NumPrevBlocks: 2,
+		PrevBlocks:    []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		MerkleRoot:    chainhash.Hash(mainNetGenesisMerkleRoot),
 
 		Timestamp: time.Unix(0x4966bc61, 0), // 2009-01-08 20:54:25 -0600 CST
 		Bits:      0x1d00ffff,               // 486604799
@@ -535,14 +540,19 @@ var blockOne = MsgBlock{
 // Block one serialized bytes.
 var blockOneBytes = []byte{
 	0x01, 0x00, 0x00, 0x00, // Version 1
-	0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+	0x02,                                           // NumPrevBlocks
+	0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 	0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 	0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-	0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-	0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
-	0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
-	0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-	0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e, // MerkleRoot
+	0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+	0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+	0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+	0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+	0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
+	0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
+	0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
+	0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 	0x61, 0xbc, 0x66, 0x49, // Timestamp
 	0xff, 0xff, 0x00, 0x1d, // Bits
 	0x01, 0xe3, 0x62, 0x99, // Nonce
@@ -576,5 +586,5 @@ var blockOneBytes = []byte{
 
 // Transaction location information for block one transactions.
 var blockOneTxLocs = []TxLoc{
-	{TxStart: 81, TxLen: 134},
+	{TxStart: 114, TxLen: 134},
 }
diff --git a/wire/msgheaders_test.go b/wire/msgheaders_test.go
index 1e44c56d2..3b363cf09 100644
--- a/wire/msgheaders_test.go
+++ b/wire/msgheaders_test.go
@@ -10,6 +10,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/daglabs/btcd/chaincfg/chainhash"
 	"github.com/davecgh/go-spew/spew"
 )
 
@@ -28,7 +29,7 @@ func TestHeaders(t *testing.T) {
 	// Ensure max payload is expected value for latest protocol version.
 	// Num headers (varInt) + max allowed headers (header length + 1 byte
 	// for the number of transactions which is always 0).
-	wantPayload := uint32(162009)
+	wantPayload := uint32(16420009)
 	maxPayload := msg.MaxPayloadLength(pver)
 	if maxPayload != wantPayload {
 		t.Errorf("MaxPayloadLength: wrong max payload length for "+
@@ -60,11 +61,11 @@ func TestHeaders(t *testing.T) {
 // TestHeadersWire tests the MsgHeaders wire encode and decode for various
 // numbers of headers and protocol versions.
 func TestHeadersWire(t *testing.T) {
-	hash := mainNetGenesisHash
+	hashes := []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash}
 	merkleHash := blockOne.Header.MerkleRoot
 	bits := uint32(0x1d00ffff)
 	nonce := uint32(0x9962e301)
-	bh := NewBlockHeader(1, &hash, &merkleHash, bits, nonce)
+	bh := NewBlockHeader(1, hashes, &merkleHash, bits, nonce)
 	bh.Version = blockOne.Header.Version
 	bh.Timestamp = blockOne.Header.Timestamp
 
@@ -80,14 +81,19 @@ func TestHeadersWire(t *testing.T) {
 	oneHeaderEncoded := []byte{
 		0x01,                   // VarInt for number of headers.
 		0x01, 0x00, 0x00, 0x00, // Version 1
-		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+		0x02,                                           // NumPrevBlocks
+		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 		0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 		0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-		0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
-		0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
-		0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-		0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e, // MerkleRoot
+		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+		0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+		0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+		0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
+		0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
+		0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
+		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 		0x61, 0xbc, 0x66, 0x49, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0x01, 0xe3, 0x62, 0x99, // Nonce
@@ -217,11 +223,11 @@ func TestHeadersWireErrors(t *testing.T) {
 	pver := ProtocolVersion
 	wireErr := &MessageError{}
 
-	hash := mainNetGenesisHash
+	hashes := []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash}
 	merkleHash := blockOne.Header.MerkleRoot
 	bits := uint32(0x1d00ffff)
 	nonce := uint32(0x9962e301)
-	bh := NewBlockHeader(1, &hash, &merkleHash, bits, nonce)
+	bh := NewBlockHeader(1, hashes, &merkleHash, bits, nonce)
 	bh.Version = blockOne.Header.Version
 	bh.Timestamp = blockOne.Header.Timestamp
 
@@ -231,14 +237,19 @@ func TestHeadersWireErrors(t *testing.T) {
 	oneHeaderEncoded := []byte{
 		0x01,                   // VarInt for number of headers.
 		0x01, 0x00, 0x00, 0x00, // Version 1
-		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+		0x02,                                           // NumPrevBlocks
+		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 		0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 		0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-		0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
-		0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
-		0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-		0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e, // MerkleRoot
+		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+		0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+		0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+		0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
+		0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
+		0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
+		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 		0x61, 0xbc, 0x66, 0x49, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0x01, 0xe3, 0x62, 0x99, // Nonce
@@ -258,7 +269,7 @@ func TestHeadersWireErrors(t *testing.T) {
 
 	// Intentionally invalid block header that has a transaction count used
 	// to force errors.
-	bhTrans := NewBlockHeader(1, &hash, &merkleHash, bits, nonce)
+	bhTrans := NewBlockHeader(1, hashes, &merkleHash, bits, nonce)
 	bhTrans.Version = blockOne.Header.Version
 	bhTrans.Timestamp = blockOne.Header.Timestamp
 
@@ -267,14 +278,19 @@ func TestHeadersWireErrors(t *testing.T) {
 	transHeaderEncoded := []byte{
 		0x01,                   // VarInt for number of headers.
 		0x01, 0x00, 0x00, 0x00, // Version 1
-		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+		0x02,                                           // NumPrevBlocks
+		0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 		0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 		0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-		0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
-		0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
-		0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-		0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e, // MerkleRoot
+		0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+		0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+		0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+		0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+		0x3b, 0xa3, 0xed, 0xfd, 0x7a, 0x7b, 0x12, 0xb2, // MerkleRoot
+		0x7a, 0xc7, 0x2c, 0x3e, 0x67, 0x76, 0x8f, 0x61,
+		0x7f, 0xc8, 0x1b, 0xc3, 0x88, 0x8a, 0x51, 0x32,
+		0x3a, 0x9f, 0xb8, 0xaa, 0x4b, 0x1e, 0x5e, 0x4a,
 		0x61, 0xbc, 0x66, 0x49, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0x01, 0xe3, 0x62, 0x99, // Nonce
@@ -297,7 +313,7 @@ func TestHeadersWireErrors(t *testing.T) {
 		// Force error with greater than max headers.
 		{maxHeaders, maxHeadersEncoded, pver, 3, wireErr, wireErr},
 		// Force error with number of transactions.
-		{transHeader, transHeaderEncoded, pver, 81, io.ErrShortWrite, io.EOF},
+		{transHeader, transHeaderEncoded, pver, 114, io.ErrShortWrite, io.EOF},
 		// Force error with included transactions.
 		{transHeader, transHeaderEncoded, pver, len(transHeaderEncoded), nil, wireErr},
 	}
diff --git a/wire/msgmerkleblock_test.go b/wire/msgmerkleblock_test.go
index 1d407f409..3ac7e9145 100644
--- a/wire/msgmerkleblock_test.go
+++ b/wire/msgmerkleblock_test.go
@@ -21,11 +21,11 @@ func TestMerkleBlock(t *testing.T) {
 	pver := ProtocolVersion
 
 	// Block 1 header.
-	prevHash := &blockOne.Header.PrevBlock
+	prevHashes := blockOne.Header.PrevBlocks
 	merkleHash := &blockOne.Header.MerkleRoot
 	bits := blockOne.Header.Bits
 	nonce := blockOne.Header.Nonce
-	bh := NewBlockHeader(1, prevHash, merkleHash, bits, nonce)
+	bh := NewBlockHeader(1, prevHashes, merkleHash, bits, nonce)
 
 	// Ensure the command is expected value.
 	wantCmd := "merkleblock"
@@ -113,11 +113,11 @@ func TestMerkleBlock(t *testing.T) {
 // the latest protocol version and decoding with BIP0031Version.
 func TestMerkleBlockCrossProtocol(t *testing.T) {
 	// Block 1 header.
-	prevHash := &blockOne.Header.PrevBlock
+	prevHashes := blockOne.Header.PrevBlocks
 	merkleHash := &blockOne.Header.MerkleRoot
 	bits := blockOne.Header.Bits
 	nonce := blockOne.Header.Nonce
-	bh := NewBlockHeader(1, prevHash, merkleHash, bits, nonce)
+	bh := NewBlockHeader(1, prevHashes, merkleHash, bits, nonce)
 
 	msg := NewMsgMerkleBlock(bh)
 
@@ -208,65 +208,33 @@ func TestMerkleBlockWireErrors(t *testing.T) {
 		readErr  error           // Expected read error
 	}{
 		// Force error in version.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 0,
-			io.ErrShortWrite, io.EOF,
-		},
-		// Force error in prev block hash.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 4,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 0, io.ErrShortWrite, io.EOF},
+		// Force error in num prev hashes.
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 4, io.ErrShortWrite, io.EOF},
+		// Force error in prev block hash #1.
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 5, io.ErrShortWrite, io.EOF},
+		// Force error in prev block hash #2.
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 37, io.ErrShortWrite, io.EOF},
 		// Force error in merkle root.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 36,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 69, io.ErrShortWrite, io.EOF},
 		// Force error in timestamp.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 68,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 101, io.ErrShortWrite, io.EOF},
 		// Force error in difficulty bits.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 72,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 105, io.ErrShortWrite, io.EOF},
 		// Force error in header nonce.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 76,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 109, io.ErrShortWrite, io.EOF},
 		// Force error in transaction count.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 80,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 113, io.ErrShortWrite, io.EOF},
 		// Force error in num hashes.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 84,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 117, io.ErrShortWrite, io.EOF},
 		// Force error in hashes.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 85,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 118, io.ErrShortWrite, io.EOF},
 		// Force error in num flag bytes.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 117,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 150, io.ErrShortWrite, io.EOF},
 		// Force error in flag bytes.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pver, 118,
-			io.ErrShortWrite, io.EOF,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 151, io.ErrShortWrite, io.EOF},
 		// Force error due to unsupported protocol version.
-		{
-			&merkleBlockOne, merkleBlockOneBytes, pverNoMerkleBlock,
-			119, wireErr, wireErr,
-		},
+		{&merkleBlockOne, merkleBlockOneBytes, pverNoMerkleBlock, 151, wireErr, wireErr},
 	}
 
 	t.Logf("Running %d tests", len(tests))
@@ -326,7 +294,7 @@ func TestMerkleBlockOverflowErrors(t *testing.T) {
 	// allowed tx hashes.
 	var buf bytes.Buffer
 	WriteVarInt(&buf, pver, maxTxPerBlock+1)
-	numHashesOffset := 84
+	numHashesOffset := 117
 	exceedMaxHashes := make([]byte, numHashesOffset)
 	copy(exceedMaxHashes, merkleBlockOneBytes[:numHashesOffset])
 	exceedMaxHashes = append(exceedMaxHashes, buf.Bytes()...)
@@ -335,7 +303,7 @@ func TestMerkleBlockOverflowErrors(t *testing.T) {
 	// allowed flag bytes.
 	buf.Reset()
 	WriteVarInt(&buf, pver, maxFlagsPerMerkleBlock+1)
-	numFlagBytesOffset := 117
+	numFlagBytesOffset := 150
 	exceedMaxFlagBytes := make([]byte, numFlagBytesOffset)
 	copy(exceedMaxFlagBytes, merkleBlockOneBytes[:numFlagBytesOffset])
 	exceedMaxFlagBytes = append(exceedMaxFlagBytes, buf.Bytes()...)
@@ -369,13 +337,9 @@ func TestMerkleBlockOverflowErrors(t *testing.T) {
 // where the first transaction matches.
 var merkleBlockOne = MsgMerkleBlock{
 	Header: BlockHeader{
-		Version: 1,
-		PrevBlock: chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
-			0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
-			0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
-			0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-			0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
-		}),
+		Version:       1,
+		NumPrevBlocks: 2,
+		PrevBlocks:    []chainhash.Hash{mainNetGenesisHash, simNetGenesisHash},
 		MerkleRoot: chainhash.Hash([chainhash.HashSize]byte{ // Make go vet happy.
 			0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
 			0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
@@ -402,14 +366,19 @@ var merkleBlockOne = MsgMerkleBlock{
 // block one of the block chain where the first transaction matches.
 var merkleBlockOneBytes = []byte{
 	0x01, 0x00, 0x00, 0x00, // Version 1
-	0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72,
+	0x02,                                           // NumPrevBlocks
+	0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, // PrevBlock mainNetGenesisHash
 	0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f,
 	0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c,
-	0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, // PrevBlock
-	0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44,
+	0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0xf6, 0x7a, 0xd7, 0x69, 0x5d, 0x9b, 0x66, 0x2a, // PrevBlock simNetGenesisHash
+	0x72, 0xff, 0x3d, 0x8e, 0xdb, 0xbb, 0x2d, 0xe0,
+	0xbf, 0xa6, 0x7b, 0x13, 0x97, 0x4b, 0xb9, 0x91,
+	0x0d, 0x11, 0x6d, 0x5c, 0xbd, 0x86, 0x3e, 0x68,
+	0x98, 0x20, 0x51, 0xfd, 0x1e, 0x4b, 0xa7, 0x44, // MerkleRoot
 	0xbb, 0xbe, 0x68, 0x0e, 0x1f, 0xee, 0x14, 0x67,
 	0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
-	0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e, // MerkleRoot
+	0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e,
 	0x61, 0xbc, 0x66, 0x49, // Timestamp
 	0xff, 0xff, 0x00, 0x1d, // Bits
 	0x01, 0xe3, 0x62, 0x99, // Nonce