diff --git a/src/hdnode.js b/src/hdnode.js
index 3c41d9e..2c14021 100644
--- a/src/hdnode.js
+++ b/src/hdnode.js
@@ -1,7 +1,8 @@
 var base58check = require('bs58check')
 var bcrypto = require('./crypto')
 var createHmac = require('create-hmac')
-var typeForce = require('typeforce')
+var typeforce = require('typeforce')
+var types = require('./types')
 var NETWORKS = require('./networks')
 
 var BigInteger = require('bigi')
@@ -11,11 +12,8 @@ var ecurve = require('ecurve')
 var curve = ecurve.getCurveByName('secp256k1')
 
 function HDNode (keyPair, chainCode) {
-  typeForce('ECPair', keyPair)
-  typeForce('Buffer', chainCode)
+  typeforce(types.tuple('ECPair', types.Buffer256bit), arguments)
 
-  if (chainCode.length !== 32) throw new TypeError('Expected chainCode length of 32, got ' + chainCode.length)
-  if (!keyPair.network.bip32) throw new TypeError('Unknown BIP32 constants for network')
   if (!keyPair.compressed) throw new TypeError('BIP32 only allows compressed keyPairs')
 
   this.keyPair = keyPair
@@ -30,7 +28,7 @@ HDNode.HIGHEST_BIT = 0x80000000
 HDNode.LENGTH = 78
 
 HDNode.fromSeedBuffer = function (seed, network) {
-  typeForce('Buffer', seed)
+  typeforce(types.tuple(types.Buffer, types.maybe(types.Network)), arguments)
 
   if (seed.length < 16) throw new TypeError('Seed should be at least 128 bits')
   if (seed.length > 64) throw new TypeError('Seed should be at most 512 bits')
diff --git a/test/hdnode.js b/test/hdnode.js
index 63a737c..3bfed8d 100644
--- a/test/hdnode.js
+++ b/test/hdnode.js
@@ -52,16 +52,8 @@ describe('HDNode', function () {
 
     it('throws when an invalid length chain code is given', function () {
       assert.throws(function () {
-        new HDNode(keyPair, chainCode.slice(0, 20))
-      }, /Expected chainCode length of 32, got 20/)
-    })
-
-    it('throws when an unknown network is given', function () {
-      keyPair.network = {}
-
-      assert.throws(function () {
-        new HDNode(keyPair, chainCode)
-      }, /Unknown BIP32 constants for network/)
+        new HDNode(keyPair, new Buffer(20))
+      }, /Expected 256-bit Buffer, got 160-bit/)
     })
   })