diff --git a/scripts/gen.js b/scripts/gen.js
index a247fb24..eeb776c6 100644
--- a/scripts/gen.js
+++ b/scripts/gen.js
@@ -2,35 +2,36 @@
 
 var bcoin = require('bcoin');
 var constants = bcoin.protocol.constants;
+var opcodes = constants.opcodes;
 var network = bcoin.protocol.network;
 var utils = bcoin.utils;
 var bn = require('bn.js');
 
 function createGenesisBlock(options) {
-  var parser = bcoin.protocol.parser;
-  var tx, block, txRaw, blockRaw;
+  var flags = options.flags;
+  var script = options.script;
+  var reward = options.reward;
+  var tx, block;
 
-  if (!options.flags) {
-    options.flags = new Buffer(
+  if (!flags) {
+    flags = new Buffer(
       'The Times 03/Jan/2009 Chancellor on brink of second bailout for banks',
       'ascii');
   }
 
-  if (!options.script) {
-    options.script = {
-      code: [
-        new Buffer('04678afdb0fe5548271967f1a67130b7105cd6a828e039'
-          + '09a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c3'
-          + '84df7ba0b8d578a4c702b6bf11d5f', 'hex'),
-        constants.opcodes.OP_CHECKSIG
-      ]
-    };
+  if (!script) {
+    script = bcoin.script.fromArray([
+      new Buffer('04678afdb0fe5548271967f1a67130b7105cd6a828e039'
+        + '09a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c3'
+        + '84df7ba0b8d578a4c702b6bf11d5f', 'hex'),
+      opcodes.OP_CHECKSIG
+    ]);
   }
 
-  if (!options.reward)
-    options.reward = 50 * constants.COIN;
+  if (!reward)
+    reward = 50 * constants.COIN;
 
-  tx = {
+  tx = new bcoin.tx({
     version: 1,
     flag: 1,
     inputs: [{
@@ -38,55 +39,31 @@ function createGenesisBlock(options) {
         hash: constants.NULL_HASH,
         index: 0xffffffff
       },
-      script: {
-        code: [
-          new bn(486604799).toBuffer('le'),
-          new bn(4).toBuffer('le'),
-          options.flags
-        ]
-      },
+      script: [
+        bcoin.opcode.fromNumber(new bn(486604799)),
+        bcoin.opcode.fromPush(new Buffer([4])),
+        bcoin.opcode.fromData(flags)
+      ],
       sequence: 0xffffffff
     }],
     outputs: [{
-      value: options.reward,
-      script: options.script
+      value: reward,
+      script: script
     }],
     locktime: 0
-  };
+  });
 
-  tx.inputs[0].script.code[1].opcode = 1;
-
-  txRaw = bcoin.protocol.framer.tx(tx);
-  tx._raw = txRaw;
-  tx._size = txRaw.length;
-  tx._witnessSize = 0;
-
-  block = {
+  block = new bcoin.block({
     version: options.version,
     prevBlock: constants.NULL_HASH,
-    merkleRoot: utils.dsha256(txRaw).toString('hex'),
+    merkleRoot: tx.hash('hex'),
     ts: options.ts,
     bits: options.bits,
     nonce: options.nonce,
-    txs: [tx]
-  };
+    height: 0
+  });
 
-  blockRaw = bcoin.protocol.framer.block(block);
-
-  block = parser.parseBlock(blockRaw);
-
-  block._hash = utils.dsha256(blockRaw.slice(0, 80));
-  block.hash = block._hash.toString('hex');
-  block._raw = blockRaw;
-  block._size = blockRaw.length;
-  block._witnessSize = 0;
-  block.height = 0;
-
-  tx = block.txs[0];
-  tx.height = 0;
-  tx.ts = block.ts;
-  tx._hash = block.merkleRoot;
-  tx.hash = tx._hash.toString('hex');
+  block.addTX(tx);
 
   return block;
 }
@@ -115,31 +92,39 @@ var regtest = createGenesisBlock({
 var segnet3 = createGenesisBlock({
   version: 1,
   ts: 1452831101,
-  bits: 0x1d00ffff,
+  bits: 486604799,
   nonce: 0
 });
 
 var segnet4 = createGenesisBlock({
   version: 1,
   ts: 1452831101,
-  bits: utils.toCompact(network.segnet4.pow.limit),
+  bits: 503447551,
   nonce: 0
 });
 
 utils.print(main);
+utils.print('');
 utils.print(testnet);
+utils.print('');
 utils.print(regtest);
+utils.print('');
 utils.print(segnet3);
-utils.print('main hash: %s', utils.revHex(main.hash));
-utils.print('main raw: %s', main._raw.toString('hex'));
 utils.print('');
-utils.print('testnet hash: %s', utils.revHex(testnet.hash));
-utils.print('testnet raw: %s', testnet._raw.toString('hex'));
-utils.print('');
-utils.print('regtest hash: %s', utils.revHex(regtest.hash));
-utils.print('regtest raw: %s', regtest._raw.toString('hex'));
-utils.print('segnet3 hash: %s', utils.revHex(segnet3.hash));
-utils.print('segnet3 raw: %s', segnet3._raw.toString('hex'));
-utils.print('segnet4 hash: %s', utils.revHex(segnet4.hash));
-utils.print('segnet4 raw: %s', segnet4._raw.toString('hex'));
 utils.print(segnet4);
+utils.print('');
+utils.print('');
+utils.print('main hash: %s', main.rhash);
+utils.print('main raw: %s', main.toRaw().toString('hex'));
+utils.print('');
+utils.print('testnet hash: %s', testnet.rhash);
+utils.print('testnet raw: %s', testnet.toRaw().toString('hex'));
+utils.print('');
+utils.print('regtest hash: %s', regtest.rhash);
+utils.print('regtest raw: %s', regtest.toRaw().toString('hex'));
+utils.print('');
+utils.print('segnet3 hash: %s', segnet3.rhash);
+utils.print('segnet3 raw: %s', segnet3.toRaw().toString('hex'));
+utils.print('');
+utils.print('segnet4 hash: %s', segnet4.rhash);
+utils.print('segnet4 raw: %s', segnet4.toRaw().toString('hex'));