diff --git a/lib/block/blockheader.js b/lib/block/blockheader.js
index 811615b..ddef34f 100644
--- a/lib/block/blockheader.js
+++ b/lib/block/blockheader.js
@@ -9,7 +9,7 @@ var Hash = require('../crypto/hash');
 var JSUtil = require('../util/js');
 var $ = require('../util/preconditions');
 
-var GENESIS_BITS = 0x2007ffff;
+var GENESIS_BITS = 0x1f07ffff;
 
 /**
  * Instantiate a BlockHeader from a Buffer, JSON object, or Object with
diff --git a/lib/networks.js b/lib/networks.js
index a4b64fd..abdbdbb 100644
--- a/lib/networks.js
+++ b/lib/networks.js
@@ -140,7 +140,7 @@ addNetwork({
   xprivkey: 0x0488ade4,
   zaddr: 0x169a,
   zkey: 0xab36,
-  networkMagic: 0xf9f3acab,
+  networkMagic: 0x24e92764,
   port: 8233,
   dnsSeeds: [
     'dnsseed.z.cash',
@@ -177,7 +177,7 @@ var testnet = get('testnet');
 
 var TESTNET = {
   PORT: 18233,
-  NETWORK_MAGIC: BufferUtil.integerAsBuffer(0xfa1a24b6),
+  NETWORK_MAGIC: BufferUtil.integerAsBuffer(0xfa1af9bf),
   DNS_SEEDS: [
     'dnsseed.testnet.z.cash',
   ]