diff --git a/examples/HierarchicalKey.js b/examples/HierarchicalKey.js
index 9e0b658..e78eb0f 100644
--- a/examples/HierarchicalKey.js
+++ b/examples/HierarchicalKey.js
@@ -10,7 +10,7 @@ var run = function() {
   console.log('https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki\n');
   console.log('1) Make new hkey from randomly generated new seed');
 
-  var randomBytes = crypto.randomBytes(256);
+  var randomBytes = crypto.randomBytes(32);
   var hkey = HierarchicalKey.seed(randomBytes);
   console.log('master extended private key: ' + hkey.extendedPrivateKeyString());
   console.log('master extended public key: ' + hkey.extendedPublicKeyString());
diff --git a/lib/HierarchicalKey.js b/lib/HierarchicalKey.js
index e220c84..4f45afb 100644
--- a/lib/HierarchicalKey.js
+++ b/lib/HierarchicalKey.js
@@ -63,6 +63,8 @@ HierarchicalKey.seed = function(bytes, network) {
     bytes = new Buffer(bytes, 'hex'); //if not buffer, assume hex
   if (bytes.length < 128/8)
     return false; //need more entropy
+  if (bytes.length > 512/8)
+    return false;
   var hash = coinUtil.sha512hmac(bytes, new Buffer('Bitcoin seed'));
 
   var hkey = new HierarchicalKey(null);