diff --git a/blockdag/blocknode.go b/blockdag/blocknode.go
index 2f2b5d037..7e1ee6ef3 100644
--- a/blockdag/blocknode.go
+++ b/blockdag/blocknode.go
@@ -97,12 +97,13 @@ type blockNode struct {
 	// reconstructing headers from memory.  These must be treated as
 	// immutable and are intentionally ordered to avoid padding on 64-bit
 	// platforms.
-	version        int32
-	bits           uint32
-	nonce          uint64
-	timestamp      int64
-	hashMerkleRoot *daghash.Hash
-	idMerkleRoot   *daghash.Hash
+	version              int32
+	bits                 uint32
+	nonce                uint64
+	timestamp            int64
+	hashMerkleRoot       *daghash.Hash
+	idMerkleRoot         *daghash.Hash
+	acceptedIDMerkleRoot *daghash.Hash
 
 	// status is a bitfield representing the validation state of the block. The
 	// status field, unlike the other fields, may be written to and so should
@@ -130,6 +131,7 @@ func initBlockNode(node *blockNode, blockHeader *wire.BlockHeader, parents block
 		node.timestamp = blockHeader.Timestamp.Unix()
 		node.hashMerkleRoot = blockHeader.HashMerkleRoot
 		node.idMerkleRoot = blockHeader.IDMerkleRoot
+		node.acceptedIDMerkleRoot = blockHeader.AcceptedIDMerkleRoot
 	} else {
 		node.hash = &daghash.ZeroHash
 	}
@@ -176,13 +178,14 @@ func (node *blockNode) updateParentsChildren() {
 func (node *blockNode) Header() *wire.BlockHeader {
 	// No lock is needed because all accessed fields are immutable.
 	return &wire.BlockHeader{
-		Version:        node.version,
-		ParentHashes:   node.ParentHashes(),
-		HashMerkleRoot: node.hashMerkleRoot,
-		IDMerkleRoot:   node.idMerkleRoot,
-		Timestamp:      time.Unix(node.timestamp, 0),
-		Bits:           node.bits,
-		Nonce:          node.nonce,
+		Version:              node.version,
+		ParentHashes:         node.ParentHashes(),
+		HashMerkleRoot:       node.hashMerkleRoot,
+		IDMerkleRoot:         node.idMerkleRoot,
+		AcceptedIDMerkleRoot: node.acceptedIDMerkleRoot,
+		Timestamp:            time.Unix(node.timestamp, 0),
+		Bits:                 node.bits,
+		Nonce:                node.nonce,
 	}
 }
 
diff --git a/blockdag/common_test.go b/blockdag/common_test.go
index 4eae34cd8..41f1f38c6 100644
--- a/blockdag/common_test.go
+++ b/blockdag/common_test.go
@@ -13,6 +13,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"strings"
+	"testing"
 	"time"
 
 	"github.com/daglabs/btcd/dagconfig"
@@ -81,6 +82,17 @@ func loadBlocks(filename string) (blocks []*util.Block, err error) {
 	return
 }
 
+func loadBlocksWithLog(t *testing.T, filename string) ([]*util.Block, error) {
+	blocks, err := loadBlocks(filename)
+	if err == nil {
+		t.Logf("Loaded %d blocks from file %s", len(blocks), filename)
+		for i, b := range blocks {
+			t.Logf("Block #%d: %s", i, b.Hash())
+		}
+	}
+	return blocks, err
+}
+
 // loadUTXOSet returns a utxo view loaded from a file.
 func loadUTXOSet(filename string) (UTXOSet, error) {
 	// The utxostore file format is:
@@ -188,12 +200,13 @@ func newTestDAG(params *dagconfig.Params) *BlockDAG {
 func newTestNode(parents blockSet, blockVersion int32, bits uint32, timestamp time.Time, phantomK uint32) *blockNode {
 	// Make up a header and create a block node from it.
 	header := &wire.BlockHeader{
-		Version:        blockVersion,
-		ParentHashes:   parents.hashes(),
-		Bits:           bits,
-		Timestamp:      timestamp,
-		HashMerkleRoot: &daghash.ZeroHash,
-		IDMerkleRoot:   &daghash.ZeroHash,
+		Version:              blockVersion,
+		ParentHashes:         parents.hashes(),
+		Bits:                 bits,
+		Timestamp:            timestamp,
+		HashMerkleRoot:       &daghash.ZeroHash,
+		IDMerkleRoot:         &daghash.ZeroHash,
+		AcceptedIDMerkleRoot: &daghash.ZeroHash,
 	}
 	return newBlockNode(header, parents, phantomK)
 }
diff --git a/blockdag/dag_test.go b/blockdag/dag_test.go
index 722f73c3b..3e3b56494 100644
--- a/blockdag/dag_test.go
+++ b/blockdag/dag_test.go
@@ -192,10 +192,10 @@ func TestHaveBlock(t *testing.T) {
 		{hash: dagconfig.SimNetParams.GenesisHash.String(), want: true},
 
 		// Block 3b should be present (as a second child of Block 2).
-		{hash: "040c43ca52ded708dacef2a9fa589f41e4f7565345f7f1e61f379dbf32bb6b48", want: true},
+		{hash: "3a81c2f7064370dddaeaf7bc7e4d282702cefb2b6e11c84942c3791c76cdd3e8", want: true},
 
 		// Block 100000 should be present (as an orphan).
-		{hash: "3da8f9ec89820deee1a4d26ff0e69c53686166ea4fbc1895fa1e0b1ccb651374", want: true},
+		{hash: "746deb238f38dfc82ea2e1dbd85c079ceb581fc2912aae37d6c3675a12545df4", want: true},
 
 		// Random hashes should not be available.
 		{hash: "123", want: false},
@@ -554,9 +554,10 @@ func chainedNodes(parents blockSet, numNodes int) []*blockNode {
 		// This is invalid, but all that is needed is enough to get the
 		// synthetic tests to work.
 		header := wire.BlockHeader{
-			Nonce:          testNoncePrng.Uint64(),
-			IDMerkleRoot:   &daghash.ZeroHash,
-			HashMerkleRoot: &daghash.ZeroHash,
+			Nonce:                testNoncePrng.Uint64(),
+			IDMerkleRoot:         &daghash.ZeroHash,
+			HashMerkleRoot:       &daghash.ZeroHash,
+			AcceptedIDMerkleRoot: &daghash.ZeroHash,
 		}
 		header.ParentHashes = tips.hashes()
 		nodes[i] = newBlockNode(&header, tips, dagconfig.SimNetParams.K)
@@ -902,10 +903,11 @@ func TestValidateFeeTransaction(t *testing.T) {
 		daghash.Sort(parentHashes)
 		msgBlock := &wire.MsgBlock{
 			Header: wire.BlockHeader{
-				Bits:           dag.genesis.Header().Bits,
-				ParentHashes:   parentHashes,
-				HashMerkleRoot: BuildHashMerkleTreeStore(utilTxs).Root(),
-				IDMerkleRoot:   BuildIDMerkleTreeStore(utilTxs).Root(),
+				Bits:                 dag.genesis.Header().Bits,
+				ParentHashes:         parentHashes,
+				HashMerkleRoot:       BuildHashMerkleTreeStore(utilTxs).Root(),
+				IDMerkleRoot:         BuildIDMerkleTreeStore(utilTxs).Root(),
+				AcceptedIDMerkleRoot: &daghash.ZeroHash,
 			},
 			Transactions: transactions,
 		}
diff --git a/blockdag/dagio.go b/blockdag/dagio.go
index 3bedc86bc..359cf727f 100644
--- a/blockdag/dagio.go
+++ b/blockdag/dagio.go
@@ -617,13 +617,14 @@ func (dag *BlockDAG) deserializeBlockNode(blockRow []byte) (*blockNode, error) {
 	}
 
 	node := &blockNode{
-		hash:           header.BlockHash(),
-		version:        header.Version,
-		bits:           header.Bits,
-		nonce:          header.Nonce,
-		timestamp:      header.Timestamp.Unix(),
-		hashMerkleRoot: header.HashMerkleRoot,
-		idMerkleRoot:   header.IDMerkleRoot,
+		hash:                 header.BlockHash(),
+		version:              header.Version,
+		bits:                 header.Bits,
+		nonce:                header.Nonce,
+		timestamp:            header.Timestamp.Unix(),
+		hashMerkleRoot:       header.HashMerkleRoot,
+		idMerkleRoot:         header.IDMerkleRoot,
+		acceptedIDMerkleRoot: header.AcceptedIDMerkleRoot,
 	}
 
 	node.children = newSet()
diff --git a/blockdag/example_test.go b/blockdag/example_test.go
index b38277fbc..70154f423 100644
--- a/blockdag/example_test.go
+++ b/blockdag/example_test.go
@@ -67,5 +67,5 @@ func ExampleBlockDAG_ProcessBlock() {
 	fmt.Printf("Block accepted. Is it an orphan?: %v", isOrphan)
 
 	// Output:
-	// Failed to process block: already have block 6477863f190fac902e556da4671c7537da4fe367022b1f00fa5270e0d073cc08
+	// Failed to process block: already have block 4aa46622896ef2f0c59aaff0c05f87984a3e640a8e79f9167f4c1b959fd14706
 }
diff --git a/blockdag/testdata/blk_0_to_4.dat b/blockdag/testdata/blk_0_to_4.dat
index 89de5696f..596084971 100644
Binary files a/blockdag/testdata/blk_0_to_4.dat and b/blockdag/testdata/blk_0_to_4.dat differ
diff --git a/blockdag/testdata/blk_3A.dat b/blockdag/testdata/blk_3A.dat
index 1e5fc5fab..58310bd73 100644
Binary files a/blockdag/testdata/blk_3A.dat and b/blockdag/testdata/blk_3A.dat differ
diff --git a/blockdag/testdata/blk_3B.dat b/blockdag/testdata/blk_3B.dat
index 2943601ac..c76b58251 100644
Binary files a/blockdag/testdata/blk_3B.dat and b/blockdag/testdata/blk_3B.dat differ
diff --git a/blockdag/testdata/blk_3C.dat b/blockdag/testdata/blk_3C.dat
index 9fae07493..0eb9ecae6 100644
Binary files a/blockdag/testdata/blk_3C.dat and b/blockdag/testdata/blk_3C.dat differ
diff --git a/blockdag/testdata/blk_3D.dat b/blockdag/testdata/blk_3D.dat
index 437ae05b1..aad54f5e7 100644
Binary files a/blockdag/testdata/blk_3D.dat and b/blockdag/testdata/blk_3D.dat differ
diff --git a/blockdag/validate_test.go b/blockdag/validate_test.go
index 5887afe39..5ebcc2f02 100644
--- a/blockdag/validate_test.go
+++ b/blockdag/validate_test.go
@@ -187,7 +187,7 @@ func TestCheckBlockSanity(t *testing.T) {
 	if !ok {
 		t.Errorf("CheckBlockSanity: wrong error returned, expect RuleError, got %T", err)
 	} else if ruleErr.ErrorCode != ErrTransactionsNotSorted {
-		t.Errorf("CheckBlockSanity: wrong error returned, expect ErrTransactionsNotSorted, got %v", ruleErr.ErrorCode)
+		t.Errorf("CheckBlockSanity: wrong error returned, expect ErrTransactionsNotSorted, got %v, err %s", ruleErr.ErrorCode, err)
 	}
 
 	// Ensure a block that has a timestamp with a precision higher than one
@@ -228,9 +228,15 @@ func TestCheckBlockSanity(t *testing.T) {
 				0x80, 0xf7, 0x00, 0xe3, 0x16, 0x3d, 0x04, 0x95,
 				0x5b, 0x7e, 0xaf, 0x84, 0x7e, 0x1b, 0x6b, 0x06,
 			},
-			Timestamp: time.Unix(0x5c40613a, 0),
+			AcceptedIDMerkleRoot: &daghash.Hash{
+				0x80, 0xf7, 0x00, 0xe3, 0x16, 0x3d, 0x04, 0x95,
+				0x5b, 0x7e, 0xaf, 0x84, 0x7e, 0x1b, 0x6b, 0x06,
+				0x4e, 0x06, 0xba, 0x64, 0xd7, 0x61, 0xda, 0x25,
+				0x1a, 0x0e, 0x21, 0xd4, 0x64, 0x49, 0x02, 0xa2,
+			},
+			Timestamp: time.Unix(0x5cd18053, 0),
 			Bits:      0x207fffff,
-			Nonce:     0x4000000000000001,
+			Nonce:     0x0,
 		},
 		Transactions: []*wire.MsgTx{
 			{
@@ -514,7 +520,7 @@ func TestCheckSerializedHeight(t *testing.T) {
 		msgTx := coinbaseTx.Copy()
 		msgTx.TxIn[0].SignatureScript = test.sigScript
 
-		msgBlock := wire.NewMsgBlock(wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0))
+		msgBlock := wire.NewMsgBlock(wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0))
 		msgBlock.AddTransaction(msgTx)
 		block := util.NewBlock(msgBlock)
 		block.SetHeight(test.wantHeight)
@@ -621,7 +627,7 @@ func TestValidateParents(t *testing.T) {
 	b := generateNode(a)
 	c := generateNode(genesisNode)
 
-	fakeBlockHeader := &wire.BlockHeader{IDMerkleRoot: &daghash.ZeroHash, HashMerkleRoot: &daghash.ZeroHash}
+	fakeBlockHeader := &wire.BlockHeader{IDMerkleRoot: &daghash.ZeroHash, HashMerkleRoot: &daghash.ZeroHash, AcceptedIDMerkleRoot: &daghash.ZeroHash}
 
 	// Check direct parents relation
 	err := validateParents(fakeBlockHeader, setFromSlice(a, b))
@@ -759,6 +765,12 @@ var Block100000 = wire.MsgBlock{
 			0x8a, 0xb7, 0xd6, 0x73, 0x1b, 0xe6, 0xc5, 0xd3,
 			0x5d, 0x4e, 0x2c, 0xc9, 0x57, 0x88, 0x30, 0x65,
 		},
+		AcceptedIDMerkleRoot: &daghash.Hash{
+			0x8a, 0xb7, 0xd6, 0x73, 0x1b, 0xe6, 0xc5, 0xd3,
+			0x5d, 0x4e, 0x2c, 0xc9, 0x57, 0x88, 0x30, 0x65,
+			0x81, 0xb8, 0xa0, 0x68, 0x77, 0xc4, 0x02, 0x1e,
+			0x3c, 0xb1, 0x16, 0x8f, 0x5f, 0x6b, 0x45, 0x87,
+		},
 		Timestamp: time.Unix(0x5c404bc3, 0),
 		Bits:      0x207fffff,
 		Nonce:     0xdffffffffffffff9,
@@ -1039,10 +1051,10 @@ var BlockWithWrongTxOrder = wire.MsgBlock{
 			},
 		},
 		HashMerkleRoot: &daghash.Hash{
-			0x0b, 0x79, 0xf5, 0x29, 0x6d, 0x1c, 0xaa, 0x90,
-			0x2f, 0x01, 0xd4, 0x83, 0x9b, 0x2a, 0x04, 0x5e,
-			0xa0, 0x69, 0x2d, 0x16, 0xb5, 0xd7, 0xe4, 0xf3,
-			0xcd, 0xc7, 0xc9, 0xaf, 0xfb, 0xd2, 0x1b, 0x85,
+			0xac, 0xa4, 0x21, 0xe1, 0xa6, 0xc3, 0xbe, 0x5d,
+			0x52, 0x66, 0xf3, 0x0b, 0x21, 0x87, 0xbc, 0xf3,
+			0xf3, 0x2d, 0xd1, 0x05, 0x64, 0xb5, 0x16, 0x76,
+			0xe4, 0x66, 0x7d, 0x51, 0x53, 0x18, 0x6d, 0xb1,
 		},
 		IDMerkleRoot: &daghash.Hash{
 			0x0b, 0x79, 0xf5, 0x29, 0x6d, 0x1c, 0xaa, 0x90,
@@ -1050,9 +1062,15 @@ var BlockWithWrongTxOrder = wire.MsgBlock{
 			0xa0, 0x69, 0x2d, 0x16, 0xb5, 0xd7, 0xe4, 0xf3,
 			0xcd, 0xc7, 0xc9, 0xaf, 0xfb, 0xd2, 0x1b, 0x85,
 		},
-		Timestamp: time.Unix(0x5c22330f, 0),
+		AcceptedIDMerkleRoot: &daghash.Hash{
+			0xa0, 0x69, 0x2d, 0x16, 0xb5, 0xd7, 0xe4, 0xf3,
+			0xcd, 0xc7, 0xc9, 0xaf, 0xfb, 0xd2, 0x1b, 0x85,
+			0x0b, 0x79, 0xf5, 0x29, 0x6d, 0x1c, 0xaa, 0x90,
+			0x2f, 0x01, 0xd4, 0x83, 0x9b, 0x2a, 0x04, 0x5e,
+		},
+		Timestamp: time.Unix(0x5cd16eaa, 0),
 		Bits:      0x207fffff,
-		Nonce:     0xdffffffffffffffc,
+		Nonce:     0x2,
 	},
 	Transactions: []*wire.MsgTx{
 		{
@@ -1188,6 +1206,8 @@ var BlockWithWrongTxOrder = wire.MsgBlock{
 			},
 			LockTime:     0,
 			SubnetworkID: subnetworkid.SubnetworkID{11},
+			Payload:      []byte{},
+			PayloadHash:  daghash.DoubleHashP([]byte{}),
 		},
 		{
 			Version: 1,
diff --git a/dagconfig/genesis.go b/dagconfig/genesis.go
index 1ef994d6e..e0972644a 100644
--- a/dagconfig/genesis.go
+++ b/dagconfig/genesis.go
@@ -41,10 +41,10 @@ var genesisCoinbaseTx = wire.NewNativeMsgTx(1, genesisTxIns, genesisTxOuts)
 // genesisHash is the hash of the first block in the block chain for the main
 // network (genesis block).
 var genesisHash = daghash.Hash([daghash.HashSize]byte{
-	0x08, 0xcc, 0x73, 0xd0, 0xe0, 0x70, 0x52, 0xfa,
-	0x00, 0x1f, 0x2b, 0x02, 0x67, 0xe3, 0x4f, 0xda,
-	0x37, 0x75, 0x1c, 0x67, 0xa4, 0x6d, 0x55, 0x2e,
-	0x90, 0xac, 0x0f, 0x19, 0x3f, 0x86, 0x77, 0x64,
+	0x06, 0x47, 0xd1, 0x9f, 0x95, 0x1b, 0x4c, 0x7f,
+	0x16, 0xf9, 0x79, 0x8e, 0x0a, 0x64, 0x3e, 0x4a,
+	0x98, 0x87, 0x5f, 0xc0, 0xf0, 0xaf, 0x9a, 0xc5,
+	0xf0, 0xf2, 0x6e, 0x89, 0x22, 0x66, 0xa4, 0x4a,
 })
 
 // genesisMerkleRoot is the hash of the first transaction in the genesis block
@@ -60,13 +60,14 @@ var genesisMerkleRoot = daghash.Hash([daghash.HashSize]byte{
 // public transaction ledger for the main network.
 var genesisBlock = wire.MsgBlock{
 	Header: wire.BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{},
-		HashMerkleRoot: &genesisMerkleRoot,
-		IDMerkleRoot:   &genesisMerkleRoot,
-		Timestamp:      time.Unix(0x5ca09ba1, 0),
-		Bits:           0x207fffff,
-		Nonce:          0x6,
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{},
+		HashMerkleRoot:       &genesisMerkleRoot,
+		IDMerkleRoot:         &genesisMerkleRoot,
+		AcceptedIDMerkleRoot: &daghash.Hash{},
+		Timestamp:            time.Unix(0x5cd00a98, 0),
+		Bits:                 0x207fffff,
+		Nonce:                0x0,
 	},
 	Transactions: []*wire.MsgTx{genesisCoinbaseTx},
 }
@@ -117,10 +118,10 @@ var devNetGenesisCoinbaseTx = genesisCoinbaseTx
 // devGenesisHash is the hash of the first block in the block chain for the development
 // network (genesis block).
 var devNetGenesisHash = daghash.Hash([daghash.HashSize]byte{
-	0xe8, 0xf0, 0x59, 0x4b, 0x54, 0xe7, 0xa1, 0xba,
-	0x1b, 0xe0, 0x6c, 0x72, 0xf8, 0x3d, 0x75, 0x5d,
-	0xa3, 0x3c, 0xc5, 0x71, 0x43, 0x94, 0x81, 0xbf,
-	0x32, 0x82, 0x5e, 0xfa, 0x6a, 0x0d, 0x00, 0x00,
+	0x90, 0x9c, 0x51, 0x90, 0x39, 0x02, 0x5e, 0x11,
+	0x52, 0xa6, 0x54, 0xff, 0xc8, 0x40, 0xdf, 0x67,
+	0x2a, 0xe8, 0x20, 0x72, 0xed, 0x6a, 0x5e, 0x3f,
+	0xf4, 0x8e, 0xf8, 0xdb, 0x02, 0x02, 0x00, 0x00,
 })
 
 // devNetGenesisMerkleRoot is the hash of the first transaction in the genesis block
@@ -131,13 +132,14 @@ var devNetGenesisMerkleRoot = genesisMerkleRoot
 // public transaction ledger for the development network.
 var devNetGenesisBlock = wire.MsgBlock{
 	Header: wire.BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{},
-		HashMerkleRoot: &devNetGenesisMerkleRoot,
-		IDMerkleRoot:   &devNetGenesisMerkleRoot,
-		Timestamp:      time.Unix(0x5ca09ba1, 0),
-		Bits:           0x1e7fffff,
-		Nonce:          0x155d9,
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{},
+		HashMerkleRoot:       &devNetGenesisMerkleRoot,
+		IDMerkleRoot:         &devNetGenesisMerkleRoot,
+		AcceptedIDMerkleRoot: &daghash.Hash{},
+		Timestamp:            time.Unix(0x5cd00a98, 0),
+		Bits:                 0x1e7fffff,
+		Nonce:                0x2f0e8,
 	},
 	Transactions: []*wire.MsgTx{devNetGenesisCoinbaseTx},
 }
diff --git a/dagconfig/genesis_test.go b/dagconfig/genesis_test.go
index 184d0c35b..9de5ea864 100644
--- a/dagconfig/genesis_test.go
+++ b/dagconfig/genesis_test.go
@@ -129,9 +129,13 @@ var genesisBlockBytes = []byte{
 	0xb8, 0x76, 0x57, 0x9d, 0x7d, 0xe9, 0x9d, 0xae,
 	0xdb, 0xf8, 0x22, 0xd2, 0x0d, 0xa2, 0xe0, 0xbb,
 	0xbe, 0xed, 0xb0, 0xdb, 0xba, 0xeb, 0x18, 0x4d,
-	0x42, 0x01, 0xff, 0xed, 0x9d, 0xa1, 0x9b, 0xa0,
+	0x42, 0x01, 0xff, 0xed, 0x9d, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x98, 0x0a, 0xd0,
 	0x5c, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0x7f,
-	0x20, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 	0x00, 0x01, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00,
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
diff --git a/database/example_test.go b/database/example_test.go
index 5c7087ead..93b1afcd1 100644
--- a/database/example_test.go
+++ b/database/example_test.go
@@ -175,5 +175,5 @@ func Example_blockStorageAndRetrieval() {
 	fmt.Printf("Serialized block size: %d bytes\n", len(loadedBlockBytes))
 
 	// Output:
-	// Serialized block size: 193 bytes
+	// Serialized block size: 225 bytes
 }
diff --git a/database/ffldb/blockio_test.go b/database/ffldb/blockio_test.go
index 871a8bd63..e1e3acd18 100644
--- a/database/ffldb/blockio_test.go
+++ b/database/ffldb/blockio_test.go
@@ -16,7 +16,7 @@ import (
 
 func TestDeleteFile(t *testing.T) {
 	testBlock := util.NewBlock(wire.NewMsgBlock(
-		wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)))
+		wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)))
 
 	tests := []struct {
 		fileNum     uint32
@@ -69,7 +69,7 @@ func TestDeleteFile(t *testing.T) {
 // and makes sure no panic occurs, as well as ensures the writeCursor was updated correctly.
 func TestHandleRollbackErrors(t *testing.T) {
 	testBlock := util.NewBlock(wire.NewMsgBlock(
-		wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)))
+		wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)))
 
 	testBlockSize := uint32(testBlock.MsgBlock().SerializeSize())
 	tests := []struct {
diff --git a/database/ffldb/db_test.go b/database/ffldb/db_test.go
index 5f993bbe2..ab1f2d768 100644
--- a/database/ffldb/db_test.go
+++ b/database/ffldb/db_test.go
@@ -553,7 +553,7 @@ func TestForEachBucket(t *testing.T) {
 // TestStoreBlockErrors tests all error-cases in *tx.StoreBlock().
 // The non-error-cases are tested in the more general tests.
 func TestStoreBlockErrors(t *testing.T) {
-	testBlock := util.NewBlock(wire.NewMsgBlock(wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)))
+	testBlock := util.NewBlock(wire.NewMsgBlock(wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)))
 
 	tests := []struct {
 		name        string
@@ -716,7 +716,7 @@ func TestWritePendingAndCommitErrors(t *testing.T) {
 	rollbackCalled = false
 	err = pdb.Update(func(dbTx database.Tx) error {
 		return dbTx.StoreBlock(util.NewBlock(wire.NewMsgBlock(
-			wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0))))
+			wire.NewBlockHeader(1, []*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0))))
 	})
 	if err == nil {
 		t.Errorf("No error returned when blockIdx.Put() should have returned an error")
diff --git a/database/testdata/blocks1-256.bz2 b/database/testdata/blocks1-256.bz2
index 9f05e5bbf..fd7350607 100644
Binary files a/database/testdata/blocks1-256.bz2 and b/database/testdata/blocks1-256.bz2 differ
diff --git a/database/testdata/generator.go b/database/testdata/generator.go
index b1aea7d46..fa65f221b 100644
--- a/database/testdata/generator.go
+++ b/database/testdata/generator.go
@@ -44,12 +44,14 @@ func generateBlocks(out *os.File, numBlocks int) {
 func generateBlock(parent *wire.MsgBlock) *wire.MsgBlock {
 	return &wire.MsgBlock{
 		Header: wire.BlockHeader{
-			Version:        1,
-			ParentHashes:   []*daghash.Hash{parent.BlockHash()},
-			HashMerkleRoot: genesisMerkleRoot,
-			Timestamp:      time.Unix(0x5b28c4c8, 0), // 2018-06-19 08:54:32 +0000 UTC
-			Bits:           0x2e00ffff,               // 503382015 [000000ffff000000000000000000000000000000000000000000000000000000]
-			Nonce:          0xc0192550,               // 2148484547
+			Version:              1,
+			ParentHashes:         []*daghash.Hash{parent.BlockHash()},
+			HashMerkleRoot:       &genesisMerkleRoot,
+			IDMerkleRoot:         &daghash.ZeroHash,
+			AcceptedIDMerkleRoot: &daghash.ZeroHash,
+			Timestamp:            time.Unix(0x5b28c4c8, 0), // 2018-06-19 08:54:32 +0000 UTC
+			Bits:                 0x2e00ffff,               // 503382015 [000000ffff000000000000000000000000000000000000000000000000000000]
+			Nonce:                0xc0192550,               // 2148484547
 		},
 		Transactions: []*wire.MsgTx{genesisCoinbaseTx},
 	}
diff --git a/integration/rpctest/blockgen.go b/integration/rpctest/blockgen.go
index eba2e93fd..2ae73007b 100644
--- a/integration/rpctest/blockgen.go
+++ b/integration/rpctest/blockgen.go
@@ -186,12 +186,13 @@ func CreateBlock(parentBlock *util.Block, inclusionTxs []*util.Tx,
 	idMerkleTree := blockdag.BuildIDMerkleTreeStore(blockTxns)
 	var block wire.MsgBlock
 	block.Header = wire.BlockHeader{
-		Version:        blockVersion,
-		ParentHashes:   []*daghash.Hash{parentHash},
-		HashMerkleRoot: hashMerkleTree.Root(),
-		IDMerkleRoot:   idMerkleTree.Root(),
-		Timestamp:      ts,
-		Bits:           net.PowLimitBits,
+		Version:              blockVersion,
+		ParentHashes:         []*daghash.Hash{parentHash},
+		HashMerkleRoot:       hashMerkleTree.Root(),
+		IDMerkleRoot:         idMerkleTree.Root(),
+		AcceptedIDMerkleRoot: &daghash.ZeroHash,
+		Timestamp:            ts,
+		Bits:                 net.PowLimitBits,
 	}
 	for _, tx := range blockTxns {
 		block.AddTransaction(tx.MsgTx())
diff --git a/mempool/estimatefee_test.go b/mempool/estimatefee_test.go
index f5bccf13c..a6c48fd34 100644
--- a/mempool/estimatefee_test.go
+++ b/mempool/estimatefee_test.go
@@ -70,7 +70,7 @@ func (eft *estimateFeeTester) newBlock(txs []*wire.MsgTx) {
 	eft.height++
 
 	block := util.NewBlock(&wire.MsgBlock{
-		Header:       wire.BlockHeader{IDMerkleRoot: &daghash.ZeroHash, HashMerkleRoot: &daghash.ZeroHash},
+		Header:       wire.BlockHeader{IDMerkleRoot: &daghash.ZeroHash, HashMerkleRoot: &daghash.ZeroHash, AcceptedIDMerkleRoot: &daghash.ZeroHash},
 		Transactions: txs,
 	})
 	block.SetHeight(eft.height)
diff --git a/mining/mining.go b/mining/mining.go
index 3bd3bb420..191930684 100644
--- a/mining/mining.go
+++ b/mining/mining.go
@@ -655,12 +655,13 @@ func (g *BlkTmplGenerator) NewBlockTemplate(payToAddress util.Address) (*BlockTe
 	idMerkleTree := blockdag.BuildIDMerkleTreeStore(blockTxns)
 	var msgBlock wire.MsgBlock
 	msgBlock.Header = wire.BlockHeader{
-		Version:        nextBlockVersion,
-		ParentHashes:   g.dag.TipHashes(),
-		HashMerkleRoot: hashMerkleTree.Root(),
-		IDMerkleRoot:   idMerkleTree.Root(),
-		Timestamp:      ts,
-		Bits:           reqDifficulty,
+		Version:              nextBlockVersion,
+		ParentHashes:         g.dag.TipHashes(),
+		HashMerkleRoot:       hashMerkleTree.Root(),
+		IDMerkleRoot:         idMerkleTree.Root(),
+		AcceptedIDMerkleRoot: &daghash.ZeroHash,
+		Timestamp:            ts,
+		Bits:                 reqDifficulty,
 	}
 	for _, tx := range blockTxns {
 		msgBlock.AddTransaction(tx.MsgTx())
diff --git a/mining/simulator/mineloop.go b/mining/simulator/mineloop.go
index 026de203f..64a40193f 100644
--- a/mining/simulator/mineloop.go
+++ b/mining/simulator/mineloop.go
@@ -37,7 +37,7 @@ func parseBlock(template *btcjson.GetBlockTemplateResult) (*util.Block, error) {
 	bits := uint32(bitsInt64)
 
 	// parse rest of block
-	msgBlock := wire.NewMsgBlock(wire.NewBlockHeader(template.Version, parentHashes, &daghash.Hash{}, &daghash.Hash{}, uint32(bits), 0))
+	msgBlock := wire.NewMsgBlock(wire.NewBlockHeader(template.Version, parentHashes, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, uint32(bits), 0))
 
 	for i, txResult := range append([]btcjson.GetBlockTemplateResultTx{*template.CoinbaseTxn}, template.Transactions...) {
 		reader := hex.NewDecoder(strings.NewReader(txResult.Data))
diff --git a/peer/peer_test.go b/peer/peer_test.go
index ca0b8f639..551c28375 100644
--- a/peer/peer_test.go
+++ b/peer/peer_test.go
@@ -494,7 +494,7 @@ func TestPeerListeners(t *testing.T) {
 		{
 			"OnBlock",
 			wire.NewMsgBlock(wire.NewBlockHeader(1,
-				[]*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 1, 1)),
+				[]*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 1, 1)),
 		},
 		{
 			"OnInv",
@@ -560,7 +560,7 @@ func TestPeerListeners(t *testing.T) {
 		{
 			"OnMerkleBlock",
 			wire.NewMsgMerkleBlock(wire.NewBlockHeader(1,
-				[]*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 1, 1)),
+				[]*daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 1, 1)),
 		},
 		// only one version message is allowed
 		// only one verack message is allowed
diff --git a/util/block_test.go b/util/block_test.go
index eb866516e..73a944c33 100644
--- a/util/block_test.go
+++ b/util/block_test.go
@@ -38,7 +38,7 @@ func TestBlock(t *testing.T) {
 	}
 
 	// Hash for block 100,000.
-	wantHashStr := "5b5168d93a5178acdf82da367f8fb85b0432874e99d5c6518adccc727fd3a012"
+	wantHashStr := "c4bb55d2eaae7c7505b199097ef163ab940aa41228bbdb6f8b6d8a5b71bc432c"
 	wantHash, err := daghash.NewHashFromStr(wantHashStr)
 	if err != nil {
 		t.Errorf("NewHashFromStr: %v", err)
@@ -147,10 +147,10 @@ func TestBlock(t *testing.T) {
 
 	// Transaction offsets and length for the transaction in Block100000.
 	wantTxLocs := []wire.TxLoc{
-		{TxStart: 154, TxLen: 163},
-		{TxStart: 317, TxLen: 287},
-		{TxStart: 604, TxLen: 285},
-		{TxStart: 889, TxLen: 253},
+		{TxStart: 186, TxLen: 163},
+		{TxStart: 349, TxLen: 287},
+		{TxStart: 636, TxLen: 285},
+		{TxStart: 921, TxLen: 253},
 	}
 
 	// Ensure the transaction location information is accurate.
@@ -259,7 +259,7 @@ func TestBlockErrors(t *testing.T) {
 	}
 
 	// Truncate the block byte buffer to force errors.
-	shortBytes := block100000Bytes[:154]
+	shortBytes := block100000Bytes[:186]
 	_, err = util.NewBlockFromBytes(shortBytes)
 	if err != io.EOF {
 		t.Errorf("NewBlockFromBytes: did not get expected error - "+
@@ -331,6 +331,12 @@ var Block100000 = wire.MsgBlock{
 			0x28, 0xc3, 0x06, 0x7c, 0xc3, 0x8d, 0x48, 0x85,
 			0xef, 0xb5, 0xa4, 0xac, 0x42, 0x47, 0xe9, 0xf3,
 		}, // f3e94742aca4b5ef85488dc37c06c3282295ffec960994b2c0d5ac2a25a95766
+		AcceptedIDMerkleRoot: &daghash.Hash{
+			0x28, 0xc3, 0x06, 0x7c, 0xc3, 0x8d, 0x48, 0x85,
+			0xef, 0xb5, 0xa4, 0xac, 0x42, 0x47, 0xe9, 0xf3,
+			0x66, 0x57, 0xa9, 0x25, 0x2a, 0xac, 0xd5, 0xc0,
+			0xb2, 0x94, 0x09, 0x96, 0xec, 0xff, 0x95, 0x22,
+		},
 		Timestamp: time.Unix(1529483563, 0), // 2018-06-20 08:32:43 +0000 UTC
 		Bits:      0x1e00ffff,               // 503382015
 		Nonce:     0x000ae53f,               // 714047
diff --git a/util/bloom/filter_test.go b/util/bloom/filter_test.go
index 6b5da3a19..283568486 100644
--- a/util/bloom/filter_test.go
+++ b/util/bloom/filter_test.go
@@ -540,6 +540,9 @@ func TestFilterInsertP2PubKeyOnly(t *testing.T) {
 		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63, 0x65, 0x9C, 0x79, // Fake IDMerkleRoot. TODO: (Ori) Replace to a real IDMerkleRoot
 		0x3C, 0xE3, 0x70, 0xD9, 0x5F, 0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11,
 		0x7B, 0x3C, 0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x3C, 0xE3, 0x70, 0xD9, 0x5F, 0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, // AcceptedIDMerkleRoot
+		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63, 0x65, 0x9C, 0x79,
+		0x7B, 0x3C, 0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
 		0x76, 0x38, 0x1B, 0x4D, 0x00, 0x00, 0x00, 0x00, // Time
 		0x4C, 0x86, 0x04, 0x1B, // Bits
 		0x55, 0x4B, 0x85, 0x29, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
diff --git a/util/bloom/merkleblock_test.go b/util/bloom/merkleblock_test.go
index 2a0db1a32..e707fe8df 100644
--- a/util/bloom/merkleblock_test.go
+++ b/util/bloom/merkleblock_test.go
@@ -28,6 +28,9 @@ func TestMerkleBlock3(t *testing.T) {
 		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63, 0x65, 0x9C, 0x79, // Fake IDMerkleRoot. TODO: (Ori) Replace to a real IDMerkleRoot
 		0x3C, 0xE3, 0x70, 0xD9, 0x5F, 0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11,
 		0x7B, 0x3C, 0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x3C, 0xE3, 0x70, 0xD9, 0x5F, 0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, // AcceptedIDMerkleRoot
+		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63, 0x65, 0x9C, 0x79,
+		0x7B, 0x3C, 0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
 		0x67, 0x29, 0x1B, 0x4D, 0x00, 0x00, 0x00, 0x00, //Time
 		0x4C, 0x86, 0x04, 0x1B, // Bits
 		0x8F, 0xA4, 0x5D, 0x63, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -81,6 +84,10 @@ func TestMerkleBlock3(t *testing.T) {
 		0x96, 0x2e, 0x8b, 0xd9, 0x63, 0x65, 0x9c, 0x79,
 		0x3c, 0xe3, 0x70, 0xd9, 0x5f, 0x09, 0x3b, 0xc7,
 		0xe3, 0x67, 0x11, 0x7b, 0x3c, 0x30, 0xc1, 0xf8,
+		0xfd, 0xd0, 0xd9, 0x72, 0x87, 0x3c, 0xe3, 0x70,
+		0xd9, 0x5f, 0x09, 0x3b, 0xc7, 0xe3, 0x67, 0x11,
+		0x7f, 0x16, 0xc5, 0x96, 0x2e, 0x8b, 0xd9, 0x63,
+		0x65, 0x9c, 0x79, 0x7b, 0x3c, 0x30, 0xc1, 0xf8,
 		0xfd, 0xd0, 0xd9, 0x72, 0x87, 0x67, 0x29, 0x1b,
 		0x4d, 0x00, 0x00, 0x00, 0x00, 0x4c, 0x86, 0x04,
 		0x1b, 0x8f, 0xa4, 0x5d, 0x63, 0x00, 0x00, 0x00,
diff --git a/wire/bench_test.go b/wire/bench_test.go
index f0b977d9d..9449172ee 100644
--- a/wire/bench_test.go
+++ b/wire/bench_test.go
@@ -426,7 +426,7 @@ func BenchmarkDecodeHeaders(b *testing.B) {
 			}
 			parentHashes[i] = hash
 		}
-		m.AddBlockHeader(NewBlockHeader(1, parentHashes, hash, hash, 0, uint64(i)))
+		m.AddBlockHeader(NewBlockHeader(1, parentHashes, hash, hash, hash, 0, uint64(i)))
 	}
 
 	// Serialize it so the bytes are available to test the decode below.
@@ -572,7 +572,7 @@ func BenchmarkDecodeMerkleBlock(b *testing.B) {
 	if err != nil {
 		b.Fatalf("NewHashFromStr: unexpected error: %v", err)
 	}
-	m.Header = *NewBlockHeader(1, []*daghash.Hash{hash}, hash, hash, 0, uint64(10000))
+	m.Header = *NewBlockHeader(1, []*daghash.Hash{hash}, hash, hash, hash, 0, uint64(10000))
 	for i := 0; i < 105; i++ {
 		hash, err := daghash.NewHashFromStr(fmt.Sprintf("%x", i))
 		if err != nil {
diff --git a/wire/blockheader.go b/wire/blockheader.go
index 54e752065..cc064e482 100644
--- a/wire/blockheader.go
+++ b/wire/blockheader.go
@@ -15,10 +15,11 @@ import (
 // BaseBlockHeaderPayload is the base number of bytes a block header can be,
 // not including the list of parent block headers.
 // Version 4 bytes + Timestamp 8 bytes + Bits 4 bytes + Nonce 8 bytes +
-// + NumParentBlocks 1 byte + HashMerkleRoot hash + IDMerkleRoot hash.
+// + NumParentBlocks 1 byte + HashMerkleRoot hash + IDMerkleRoot hash +
+// + AcceptedIDMerkleRoot hash.
 // To get total size of block header len(ParentHashes) * daghash.HashSize should be
 // added to this value
-const BaseBlockHeaderPayload = 25 + 2*(daghash.HashSize)
+const BaseBlockHeaderPayload = 25 + 3*(daghash.HashSize)
 
 // MaxNumParentBlocks is the maximum number of parent blocks a block can reference.
 // Currently set to 255 as the maximum number NumParentBlocks can be due to it being a byte
@@ -43,6 +44,10 @@ type BlockHeader struct {
 	// IDMerkleRoot is the merkle tree reference to hash of all transactions' IDs for the block.
 	IDMerkleRoot *daghash.Hash
 
+	// AcceptedIDMerkleRoot is merkle tree reference to hash all transactions
+	// accepted form the block.Blues
+	AcceptedIDMerkleRoot *daghash.Hash
+
 	// Time the block was created.
 	Timestamp time.Time
 
@@ -121,18 +126,20 @@ func (h *BlockHeader) SerializeSize() int {
 // block hash, hash merkle root, ID merkle root difficulty bits, and nonce used to generate the
 // block with defaults or calclulated values for the remaining fields.
 func NewBlockHeader(version int32, parentHashes []*daghash.Hash, hashMerkleRoot *daghash.Hash,
-	idMerkleRoot *daghash.Hash, bits uint32, nonce uint64) *BlockHeader {
+	idMerkleRoot *daghash.Hash, acceptedIDMerkleRoot *daghash.Hash,
+	bits uint32, nonce uint64) *BlockHeader {
 
 	// Limit the timestamp to one second precision since the protocol
 	// doesn't support better.
 	return &BlockHeader{
-		Version:        version,
-		ParentHashes:   parentHashes,
-		HashMerkleRoot: hashMerkleRoot,
-		IDMerkleRoot:   idMerkleRoot,
-		Timestamp:      time.Unix(time.Now().Unix(), 0),
-		Bits:           bits,
-		Nonce:          nonce,
+		Version:              version,
+		ParentHashes:         parentHashes,
+		HashMerkleRoot:       hashMerkleRoot,
+		IDMerkleRoot:         idMerkleRoot,
+		AcceptedIDMerkleRoot: acceptedIDMerkleRoot,
+		Timestamp:            time.Unix(time.Now().Unix(), 0),
+		Bits:                 bits,
+		Nonce:                nonce,
 	}
 }
 
@@ -157,7 +164,10 @@ func readBlockHeader(r io.Reader, pver uint32, bh *BlockHeader) error {
 	}
 	bh.HashMerkleRoot = &daghash.Hash{}
 	bh.IDMerkleRoot = &daghash.Hash{}
-	return readElements(r, bh.HashMerkleRoot, bh.IDMerkleRoot, (*int64Time)(&bh.Timestamp), &bh.Bits, &bh.Nonce)
+	bh.AcceptedIDMerkleRoot = &daghash.Hash{}
+	return readElements(r, bh.HashMerkleRoot, bh.IDMerkleRoot,
+		bh.AcceptedIDMerkleRoot, (*int64Time)(&bh.Timestamp),
+		&bh.Bits, &bh.Nonce)
 }
 
 // writeBlockHeader writes a bitcoin block header to w.  See Serialize for
@@ -174,5 +184,5 @@ func writeBlockHeader(w io.Writer, pver uint32, bh *BlockHeader) error {
 		}
 	}
 	return writeElements(w, bh.HashMerkleRoot, bh.IDMerkleRoot,
-		sec, bh.Bits, bh.Nonce)
+		bh.AcceptedIDMerkleRoot, sec, bh.Bits, bh.Nonce)
 }
diff --git a/wire/blockheader_test.go b/wire/blockheader_test.go
index a6cf8bcee..446cce2ca 100644
--- a/wire/blockheader_test.go
+++ b/wire/blockheader_test.go
@@ -26,8 +26,10 @@ func TestBlockHeader(t *testing.T) {
 
 	merkleHash := mainNetGenesisMerkleRoot
 	idMerkleRoot := exampleIDMerkleRoot
+	acceptedIDMerkleRoot := exampleAcceptedIDMerkleRoot
 	bits := uint32(0x1d00ffff)
-	bh := NewBlockHeader(1, hashes, merkleHash, idMerkleRoot, bits, nonce)
+	bh := NewBlockHeader(1, hashes, merkleHash, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 
 	// Ensure we get the same data back out.
 	if !reflect.DeepEqual(bh.ParentHashes, hashes) {
@@ -57,13 +59,14 @@ func TestBlockHeaderWire(t *testing.T) {
 	// baseBlockHdr is used in the various tests as a baseline BlockHeader.
 	bits := uint32(0x1d00ffff)
 	baseBlockHdr := &BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
-		HashMerkleRoot: mainNetGenesisMerkleRoot,
-		IDMerkleRoot:   exampleIDMerkleRoot,
-		Timestamp:      time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
-		Bits:           bits,
-		Nonce:          nonce,
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		HashMerkleRoot:       mainNetGenesisMerkleRoot,
+		IDMerkleRoot:         exampleIDMerkleRoot,
+		AcceptedIDMerkleRoot: exampleAcceptedIDMerkleRoot,
+		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.
@@ -86,6 +89,10 @@ func TestBlockHeaderWire(t *testing.T) {
 		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x29, 0xab, 0x5f, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0xf3, 0xe0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -168,13 +175,14 @@ func TestBlockHeaderSerialize(t *testing.T) {
 	// baseBlockHdr is used in the various tests as a baseline BlockHeader.
 	bits := uint32(0x1d00ffff)
 	baseBlockHdr := &BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
-		HashMerkleRoot: mainNetGenesisMerkleRoot,
-		IDMerkleRoot:   exampleIDMerkleRoot,
-		Timestamp:      time.Unix(0x495fab29, 0), // 2009-01-03 12:15:05 -0600 CST
-		Bits:           bits,
-		Nonce:          nonce,
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		HashMerkleRoot:       mainNetGenesisMerkleRoot,
+		IDMerkleRoot:         exampleIDMerkleRoot,
+		AcceptedIDMerkleRoot: exampleAcceptedIDMerkleRoot,
+		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.
@@ -197,6 +205,10 @@ func TestBlockHeaderSerialize(t *testing.T) {
 		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x29, 0xab, 0x5f, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0xf3, 0xe0, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -252,33 +264,35 @@ func TestBlockHeaderSerializeSize(t *testing.T) {
 	bits := uint32(0x1d00ffff)
 	timestamp := time.Unix(0x495fab29, 0) // 2009-01-03 12:15:05 -0600 CST
 	baseBlockHdr := &BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
-		HashMerkleRoot: mainNetGenesisMerkleRoot,
-		IDMerkleRoot:   mainNetGenesisMerkleRoot,
-		Timestamp:      timestamp,
-		Bits:           bits,
-		Nonce:          nonce,
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		HashMerkleRoot:       mainNetGenesisMerkleRoot,
+		IDMerkleRoot:         mainNetGenesisMerkleRoot,
+		AcceptedIDMerkleRoot: &daghash.ZeroHash,
+		Timestamp:            timestamp,
+		Bits:                 bits,
+		Nonce:                nonce,
 	}
 
 	genesisBlockHdr := &BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{},
-		HashMerkleRoot: mainNetGenesisMerkleRoot,
-		IDMerkleRoot:   mainNetGenesisMerkleRoot,
-		Timestamp:      timestamp,
-		Bits:           bits,
-		Nonce:          nonce,
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{},
+		HashMerkleRoot:       mainNetGenesisMerkleRoot,
+		IDMerkleRoot:         mainNetGenesisMerkleRoot,
+		AcceptedIDMerkleRoot: &daghash.ZeroHash,
+		Timestamp:            timestamp,
+		Bits:                 bits,
+		Nonce:                nonce,
 	}
 	tests := []struct {
 		in   *BlockHeader // Block header to encode
 		size int          // Expected serialized size
 	}{
 		// Block with no transactions.
-		{genesisBlockHdr, 89},
+		{genesisBlockHdr, 121},
 
 		// First block in the mainnet block DAG.
-		{baseBlockHdr, 153},
+		{baseBlockHdr, 185},
 	}
 
 	t.Logf("Running %d tests", len(tests))
diff --git a/wire/common_test.go b/wire/common_test.go
index 3551a25fa..9bd7a876b 100644
--- a/wire/common_test.go
+++ b/wire/common_test.go
@@ -49,6 +49,13 @@ var exampleIDMerkleRoot = &daghash.Hash{
 	0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
 }
 
+var exampleAcceptedIDMerkleRoot = &daghash.Hash{
+	0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
+	0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+	0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+	0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
+}
+
 // TestElementWire tests wire encode and decode for various element types.  This
 // is mainly to test the "fast" paths in readElement and writeElement which use
 // type assertions to avoid reflection when possible.
diff --git a/wire/message_test.go b/wire/message_test.go
index d81e9dbc8..455723034 100644
--- a/wire/message_test.go
+++ b/wire/message_test.go
@@ -68,7 +68,7 @@ func TestMessage(t *testing.T) {
 	msgFilterAdd := NewMsgFilterAdd([]byte{0x01})
 	msgFilterClear := NewMsgFilterClear()
 	msgFilterLoad := NewMsgFilterLoad([]byte{0x01}, 10, 0, BloomUpdateNone)
-	bh := NewBlockHeader(1, []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)
+	bh := NewBlockHeader(1, []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash}, &daghash.Hash{}, &daghash.Hash{}, &daghash.Hash{}, 0, 0)
 	msgMerkleBlock := NewMsgMerkleBlock(bh)
 	msgReject := NewMsgReject("block", RejectDuplicate, "duplicate block")
 	msgGetCFilters := NewMsgGetCFilters(GCSFilterExtended, 0, &daghash.Hash{})
@@ -91,7 +91,7 @@ func TestMessage(t *testing.T) {
 		{msgGetAddr, msgGetAddr, pver, MainNet, 26},
 		{msgAddr, msgAddr, pver, MainNet, 27},
 		{msgGetBlocks, msgGetBlocks, pver, MainNet, 61},
-		{msgBlock, msgBlock, pver, MainNet, 340},
+		{msgBlock, msgBlock, pver, MainNet, 372},
 		{msgInv, msgInv, pver, MainNet, 25},
 		{msgGetData, msgGetData, pver, MainNet, 25},
 		{msgNotFound, msgNotFound, pver, MainNet, 25},
@@ -107,7 +107,7 @@ func TestMessage(t *testing.T) {
 		{msgFilterAdd, msgFilterAdd, pver, MainNet, 26},
 		{msgFilterClear, msgFilterClear, pver, MainNet, 24},
 		{msgFilterLoad, msgFilterLoad, pver, MainNet, 35},
-		{msgMerkleBlock, msgMerkleBlock, pver, MainNet, 183},
+		{msgMerkleBlock, msgMerkleBlock, pver, MainNet, 215},
 		{msgReject, msgReject, pver, MainNet, 79},
 		{msgGetCFilters, msgGetCFilters, pver, MainNet, 65},
 		{msgGetCFHeaders, msgGetCFHeaders, pver, MainNet, 65},
diff --git a/wire/msgblock_test.go b/wire/msgblock_test.go
index 331a91bf8..dc2f0a736 100644
--- a/wire/msgblock_test.go
+++ b/wire/msgblock_test.go
@@ -26,9 +26,11 @@ func TestBlock(t *testing.T) {
 	parentHashes := blockOne.Header.ParentHashes
 	hashMerkleRoot := blockOne.Header.HashMerkleRoot
 	idMerkleRoot := blockOne.Header.IDMerkleRoot
+	acceptedIDMerkleRoot := blockOne.Header.AcceptedIDMerkleRoot
 	bits := blockOne.Header.Bits
 	nonce := blockOne.Header.Nonce
-	bh := NewBlockHeader(1, parentHashes, hashMerkleRoot, idMerkleRoot, bits, nonce)
+	bh := NewBlockHeader(1, parentHashes, hashMerkleRoot, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 
 	// Ensure the command is expected value.
 	wantCmd := "block"
@@ -74,7 +76,7 @@ func TestBlock(t *testing.T) {
 // TestBlockHash tests the ability to generate the hash of a block accurately.
 func TestBlockHash(t *testing.T) {
 	// Block 1 hash.
-	hashStr := "67ec32b619b4cda3255de5318c730e2e9f696d335427adfecae884aa41156b0f"
+	hashStr := "d632f80af4f507bed094a424902e37cc4b1e447e4ede731f0f4b446edebaf381"
 	wantHash, err := daghash.NewHashFromStr(hashStr)
 	if err != nil {
 		t.Errorf("NewHashFromStr: %v", err)
@@ -220,16 +222,18 @@ func TestBlockWireErrors(t *testing.T) {
 		{&blockOne, blockOneBytes, pver, 69, io.ErrShortWrite, io.EOF},
 		// Force error in ID merkle root.
 		{&blockOne, blockOneBytes, pver, 101, io.ErrShortWrite, io.EOF},
-		// Force error in timestamp.
+		// Force error in accepted ID merkle root.
 		{&blockOne, blockOneBytes, pver, 133, io.ErrShortWrite, io.EOF},
+		// Force error in timestamp.
+		{&blockOne, blockOneBytes, pver, 165, io.ErrShortWrite, io.EOF},
 		// Force error in difficulty bits.
-		{&blockOne, blockOneBytes, pver, 141, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 173, io.ErrShortWrite, io.EOF},
 		// Force error in header nonce.
-		{&blockOne, blockOneBytes, pver, 145, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 177, io.ErrShortWrite, io.EOF},
 		// Force error in transaction count.
-		{&blockOne, blockOneBytes, pver, 153, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 185, io.ErrShortWrite, io.EOF},
 		// Force error in transactions.
-		{&blockOne, blockOneBytes, pver, 154, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, pver, 186, io.ErrShortWrite, io.EOF},
 	}
 
 	t.Logf("Running %d tests", len(tests))
@@ -344,16 +348,18 @@ func TestBlockSerializeErrors(t *testing.T) {
 		{&blockOne, blockOneBytes, 69, io.ErrShortWrite, io.EOF},
 		// Force error in ID merkle root.
 		{&blockOne, blockOneBytes, 101, io.ErrShortWrite, io.EOF},
-		// Force error in timestamp.
+		// Force error in accepted ID merkle root.
 		{&blockOne, blockOneBytes, 133, io.ErrShortWrite, io.EOF},
+		// Force error in timestamp.
+		{&blockOne, blockOneBytes, 165, io.ErrShortWrite, io.EOF},
 		// Force error in difficulty bits.
-		{&blockOne, blockOneBytes, 141, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 173, io.ErrShortWrite, io.EOF},
 		// Force error in header nonce.
-		{&blockOne, blockOneBytes, 145, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 177, io.ErrShortWrite, io.EOF},
 		// Force error in transaction count.
-		{&blockOne, blockOneBytes, 153, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 185, io.ErrShortWrite, io.EOF},
 		// Force error in transactions.
-		{&blockOne, blockOneBytes, 154, io.ErrShortWrite, io.EOF},
+		{&blockOne, blockOneBytes, 186, io.ErrShortWrite, io.EOF},
 	}
 
 	t.Logf("Running %d tests", len(tests))
@@ -421,6 +427,10 @@ func TestBlockOverflowErrors(t *testing.T) {
 				0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 				0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 				0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+				0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+				0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+				0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+				0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 				0x61, 0xbc, 0x66, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 				0xff, 0xff, 0x00, 0x1d, // Bits
 				0x01, 0xe3, 0x62, 0x99, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -473,7 +483,7 @@ func TestBlockSerializeSize(t *testing.T) {
 		size int       // Expected serialized size
 	}{
 		// Block with no transactions.
-		{noTxBlock, 154},
+		{noTxBlock, 186},
 
 		// First block in the mainnet block chain.
 		{&blockOne, len(blockOneBytes)},
@@ -494,13 +504,14 @@ func TestBlockSerializeSize(t *testing.T) {
 // blockOne is the first block in the mainnet block chain.
 var blockOne = MsgBlock{
 	Header: BlockHeader{
-		Version:        1,
-		ParentHashes:   []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
-		HashMerkleRoot: mainNetGenesisMerkleRoot,
-		IDMerkleRoot:   exampleIDMerkleRoot,
-		Timestamp:      time.Unix(0x4966bc61, 0), // 2009-01-08 20:54:25 -0600 CST
-		Bits:           0x1d00ffff,               // 486604799
-		Nonce:          0x9962e301,               // 2573394689
+		Version:              1,
+		ParentHashes:         []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash},
+		HashMerkleRoot:       mainNetGenesisMerkleRoot,
+		IDMerkleRoot:         exampleIDMerkleRoot,
+		AcceptedIDMerkleRoot: exampleAcceptedIDMerkleRoot,
+		Timestamp:            time.Unix(0x4966bc61, 0), // 2009-01-08 20:54:25 -0600 CST
+		Bits:                 0x1d00ffff,               // 486604799
+		Nonce:                0x9962e301,               // 2573394689
 	},
 	Transactions: []*MsgTx{
 		NewNativeMsgTx(1,
@@ -557,6 +568,10 @@ var blockOneBytes = []byte{
 	0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 	0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 	0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+	0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+	0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+	0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+	0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 	0x61, 0xbc, 0x66, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 	0xff, 0xff, 0x00, 0x1d, // Bits
 	0x01, 0xe3, 0x62, 0x99, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -593,5 +608,5 @@ var blockOneBytes = []byte{
 
 // Transaction location information for block one transactions.
 var blockOneTxLocs = []TxLoc{
-	{TxStart: 154, TxLen: 162},
+	{TxStart: 186, TxLen: 162},
 }
diff --git a/wire/msgheaders_test.go b/wire/msgheaders_test.go
index b72ecaee2..60ba771ed 100644
--- a/wire/msgheaders_test.go
+++ b/wire/msgheaders_test.go
@@ -29,7 +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(16500009)
+	wantPayload := uint32(16564009)
 	maxPayload := msg.MaxPayloadLength(pver)
 	if maxPayload != wantPayload {
 		t.Errorf("MaxPayloadLength: wrong max payload length for "+
@@ -64,9 +64,11 @@ func TestHeadersWire(t *testing.T) {
 	hashes := []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash}
 	hashMerkleRoot := blockOne.Header.HashMerkleRoot
 	idMerkleRoot := blockOne.Header.IDMerkleRoot
+	acceptedIDMerkleRoot := blockOne.Header.AcceptedIDMerkleRoot
 	bits := uint32(0x1d00ffff)
 	nonce := uint64(0x9962e301)
-	bh := NewBlockHeader(1, hashes, hashMerkleRoot, idMerkleRoot, bits, nonce)
+	bh := NewBlockHeader(1, hashes, hashMerkleRoot, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 	bh.Version = blockOne.Header.Version
 	bh.Timestamp = blockOne.Header.Timestamp
 
@@ -99,6 +101,10 @@ func TestHeadersWire(t *testing.T) {
 		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x61, 0xbc, 0x66, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0x01, 0xe3, 0x62, 0x99, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -168,9 +174,11 @@ func TestHeadersWireErrors(t *testing.T) {
 	hashes := []*daghash.Hash{mainNetGenesisHash, simNetGenesisHash}
 	hashMerkleRoot := blockOne.Header.HashMerkleRoot
 	idMerkleRoot := blockOne.Header.IDMerkleRoot
+	acceptedIDMerkleRoot := blockOne.Header.AcceptedIDMerkleRoot
 	bits := uint32(0x1d00ffff)
 	nonce := uint64(0x9962e301)
-	bh := NewBlockHeader(1, hashes, hashMerkleRoot, idMerkleRoot, bits, nonce)
+	bh := NewBlockHeader(1, hashes, hashMerkleRoot, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 	bh.Version = blockOne.Header.Version
 	bh.Timestamp = blockOne.Header.Timestamp
 
@@ -216,7 +224,8 @@ func TestHeadersWireErrors(t *testing.T) {
 
 	// Intentionally invalid block header that has a transaction count used
 	// to force errors.
-	bhTrans := NewBlockHeader(1, hashes, hashMerkleRoot, idMerkleRoot, bits, nonce)
+	bhTrans := NewBlockHeader(1, hashes, hashMerkleRoot, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 	bhTrans.Version = blockOne.Header.Version
 	bhTrans.Timestamp = blockOne.Header.Timestamp
 
@@ -242,6 +251,10 @@ func TestHeadersWireErrors(t *testing.T) {
 		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+		0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+		0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+		0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 		0x61, 0xbc, 0x66, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 		0xff, 0xff, 0x00, 0x1d, // Bits
 		0x01, 0xe3, 0x62, 0x99, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce
@@ -264,7 +277,7 @@ 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, 146, io.ErrShortWrite, io.EOF},
+		{transHeader, transHeaderEncoded, pver, 178, 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 328493a03..d5c2bae24 100644
--- a/wire/msgmerkleblock_test.go
+++ b/wire/msgmerkleblock_test.go
@@ -24,9 +24,11 @@ func TestMerkleBlock(t *testing.T) {
 	parentHashes := blockOne.Header.ParentHashes
 	hashMerkleRoot := blockOne.Header.HashMerkleRoot
 	idMerkleRoot := blockOne.Header.IDMerkleRoot
+	acceptedIDMerkleRoot := blockOne.Header.AcceptedIDMerkleRoot
 	bits := blockOne.Header.Bits
 	nonce := blockOne.Header.Nonce
-	bh := NewBlockHeader(1, parentHashes, hashMerkleRoot, idMerkleRoot, bits, nonce)
+	bh := NewBlockHeader(1, parentHashes, hashMerkleRoot, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 
 	// Ensure the command is expected value.
 	wantCmd := "merkleblock"
@@ -117,9 +119,11 @@ func TestMerkleBlockCrossProtocol(t *testing.T) {
 	parentHashes := blockOne.Header.ParentHashes
 	hashMerkleRoot := blockOne.Header.HashMerkleRoot
 	idMerkleRoot := blockOne.Header.IDMerkleRoot
+	acceptedIDMerkleRoot := blockOne.Header.AcceptedIDMerkleRoot
 	bits := blockOne.Header.Bits
 	nonce := blockOne.Header.Nonce
-	bh := NewBlockHeader(1, parentHashes, hashMerkleRoot, idMerkleRoot, bits, nonce)
+	bh := NewBlockHeader(1, parentHashes, hashMerkleRoot, idMerkleRoot,
+		acceptedIDMerkleRoot, bits, nonce)
 
 	msg := NewMsgMerkleBlock(bh)
 
@@ -203,22 +207,24 @@ func TestMerkleBlockWireErrors(t *testing.T) {
 		{&merkleBlockOne, merkleBlockOneBytes, pver, 69, io.ErrShortWrite, io.EOF},
 		// Force error in hash merkle root.
 		{&merkleBlockOne, merkleBlockOneBytes, pver, 101, io.ErrShortWrite, io.EOF},
-		// Force error in timestamp.
+		// Force error in accepted ID merkle root.
 		{&merkleBlockOne, merkleBlockOneBytes, pver, 133, io.ErrShortWrite, io.EOF},
+		// Force error in timestamp.
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 165, io.ErrShortWrite, io.EOF},
 		// Force error in difficulty bits.
-		{&merkleBlockOne, merkleBlockOneBytes, pver, 141, io.ErrShortWrite, io.EOF},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 173, io.ErrShortWrite, io.EOF},
 		// Force error in header nonce.
-		{&merkleBlockOne, merkleBlockOneBytes, pver, 145, io.ErrShortWrite, io.EOF},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 177, io.ErrShortWrite, io.EOF},
 		// Force error in transaction count.
-		{&merkleBlockOne, merkleBlockOneBytes, pver, 153, io.ErrShortWrite, io.EOF},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 185, io.ErrShortWrite, io.EOF},
 		// Force error in num hashes.
-		{&merkleBlockOne, merkleBlockOneBytes, pver, 157, io.ErrShortWrite, io.EOF},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 189, io.ErrShortWrite, io.EOF},
 		// Force error in hashes.
-		{&merkleBlockOne, merkleBlockOneBytes, pver, 158, io.ErrShortWrite, io.EOF},
-		// Force error in num flag bytes.
 		{&merkleBlockOne, merkleBlockOneBytes, pver, 190, io.ErrShortWrite, io.EOF},
+		// Force error in num flag bytes.
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 222, io.ErrShortWrite, io.EOF},
 		// Force error in flag bytes.
-		{&merkleBlockOne, merkleBlockOneBytes, pver, 191, io.ErrShortWrite, io.EOF},
+		{&merkleBlockOne, merkleBlockOneBytes, pver, 223, io.ErrShortWrite, io.EOF},
 	}
 
 	t.Logf("Running %d tests", len(tests))
@@ -275,7 +281,7 @@ func TestMerkleBlockOverflowErrors(t *testing.T) {
 	// allowed tx hashes.
 	var buf bytes.Buffer
 	WriteVarInt(&buf, maxTxPerBlock+1)
-	numHashesOffset := 157
+	numHashesOffset := 189
 	exceedMaxHashes := make([]byte, numHashesOffset)
 	copy(exceedMaxHashes, merkleBlockOneBytes[:numHashesOffset])
 	exceedMaxHashes = append(exceedMaxHashes, buf.Bytes()...)
@@ -284,7 +290,7 @@ func TestMerkleBlockOverflowErrors(t *testing.T) {
 	// allowed flag bytes.
 	buf.Reset()
 	WriteVarInt(&buf, maxFlagsPerMerkleBlock+1)
-	numFlagBytesOffset := 190
+	numFlagBytesOffset := 222
 	exceedMaxFlagBytes := make([]byte, numFlagBytesOffset)
 	copy(exceedMaxFlagBytes, merkleBlockOneBytes[:numFlagBytesOffset])
 	exceedMaxFlagBytes = append(exceedMaxFlagBytes, buf.Bytes()...)
@@ -326,10 +332,11 @@ var merkleBlockOne = MsgMerkleBlock{
 			0x7b, 0xa1, 0xa3, 0xc3, 0x54, 0x0b, 0xf7, 0xb1,
 			0xcd, 0xb6, 0x06, 0xe8, 0x57, 0x23, 0x3e, 0x0e,
 		},
-		IDMerkleRoot: exampleIDMerkleRoot,
-		Timestamp:    time.Unix(0x4966bc61, 0), // 2009-01-08 20:54:25 -0600 CST
-		Bits:         0x1d00ffff,               // 486604799
-		Nonce:        0x9962e301,               // 2573394689
+		IDMerkleRoot:         exampleIDMerkleRoot,
+		AcceptedIDMerkleRoot: exampleAcceptedIDMerkleRoot,
+		Timestamp:            time.Unix(0x4966bc61, 0), // 2009-01-08 20:54:25 -0600 CST
+		Bits:                 0x1d00ffff,               // 486604799
+		Nonce:                0x9962e301,               // 2573394689
 	},
 	Transactions: 1,
 	Hashes: []*daghash.Hash{
@@ -364,6 +371,10 @@ var merkleBlockOneBytes = []byte{
 	0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 	0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C,
 	0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+	0x09, 0x3B, 0xC7, 0xE3, 0x67, 0x11, 0x7B, 0x3C, // AcceptedIDMerkleRoot
+	0x30, 0xC1, 0xF8, 0xFD, 0xD0, 0xD9, 0x72, 0x87,
+	0x7F, 0x16, 0xC5, 0x96, 0x2E, 0x8B, 0xD9, 0x63,
+	0x65, 0x9C, 0x79, 0x3C, 0xE3, 0x70, 0xD9, 0x5F,
 	0x61, 0xbc, 0x66, 0x49, 0x00, 0x00, 0x00, 0x00, // Timestamp
 	0xff, 0xff, 0x00, 0x1d, // Bits
 	0x01, 0xe3, 0x62, 0x99, 0x00, 0x00, 0x00, 0x00, // Fake Nonce. TODO: (Ori) Replace to a real nonce