diff --git a/lib/privatekey.js b/lib/privatekey.js
index 8560f6852..dfd4638a5 100644
--- a/lib/privatekey.js
+++ b/lib/privatekey.js
@@ -157,11 +157,8 @@ PrivateKey._transformBuffer = function(buf, network) {
   }
 
   info.network = Networks.get(buf[0], 'privatekey');
-  if (buf[0] === Networks.livenet.privatekey) {
-    info.network = Networks.livenet;
-  } else if (buf[0] === Networks.testnet.privatekey) {
-    info.network = Networks.testnet;
-  } else {
+
+  if (!info.network) {
     throw new Error('Invalid network');
   }
 
diff --git a/test/networks.js b/test/networks.js
index 989e06481..c3f9b8be1 100644
--- a/test/networks.js
+++ b/test/networks.js
@@ -48,7 +48,7 @@ describe('Networks', function() {
     var net = networks.get('customnet');
     should.equal(net, undefined);
   });
-  
+
   it('should not set a network map for an undefined value', function() {
     var custom = {
       name: 'somenet',
diff --git a/test/privatekey.js b/test/privatekey.js
index 03aad24e8..006fb7301 100644
--- a/test/privatekey.js
+++ b/test/privatekey.js
@@ -22,6 +22,7 @@ describe('PrivateKey', function() {
   var wifTestnetUncompressed = '92jJzK4tbURm1C7udQXxeCBvXHoHJstDXRxAMouPG1k1XUaXdsu';
   var wifLivenet = 'L2Gkw3kKJ6N24QcDuH4XDqt9cTqsKTVNDGz1CRZhk9cq4auDUbJy';
   var wifLivenetUncompressed = '5JxgQaFM1FMd38cd14e3mbdxsdSa9iM2BV6DHBYsvGzxkTNQ7Un';
+  var wifNamecoin = '74pxNKNpByQ2kMow4d9kF6Z77BYeKztQNLq3dSyU4ES1K5KLNiz';
 
   it('should create a new random private key', function() {
     var a = new PrivateKey();
@@ -44,6 +45,31 @@ describe('PrivateKey', function() {
     should.exist(a.bn);
   });
 
+  it('should create a private key from a custom network WIF string', function() {
+    var nmc = {
+      name: 'namecoin',
+      alias: 'namecoin',
+      pubkeyhash: 0x34,
+      privatekey: 0xB4,
+      // these below aren't the real NMC version numbers
+      scripthash: 0x08,
+      xpubkey: 0x0278b20e,
+      xprivkey: 0x0278ade4,
+      networkMagic: 0xf9beb4fe,
+      port: 20001,
+      dnsSeeds: [
+        'localhost',
+        'mynet.localhost'
+      ]
+    };
+    Networks.add(nmc);
+    var nmcNet = Networks.get('namecoin');
+    var a = new PrivateKey(wifNamecoin, nmcNet);
+    should.exist(a);
+    should.exist(a.bn);
+    Networks.remove(nmcNet);
+  });
+
   it('should create a new random testnet private key with empty data', function() {
     var a = new PrivateKey(null, Networks.testnet);
     should.exist(a);
@@ -114,6 +140,12 @@ describe('PrivateKey', function() {
       }).to.throw('Invalid network');
     });
 
+    it('should not be able to instantiate private key WIF because of network mismatch', function() {
+      expect(function(){
+        var a = new PrivateKey(wifNamecoin, 'testnet');
+      }).to.throw('Invalid network');
+    });
+
     it('can be instantiated from a hex string', function() {
       var privhex = '906977a061af29276e40bf377042ffbde414e496ae2260bbf1fa9d085637bfff';
       var pubhex = '02a1633cafcc01ebfb6d78e39f687a1f0995c62fc95f51ead10a02ee0be551b5dc';