diff --git a/cmd.py b/cmd.py
index 920394779..276eb41d1 100755
--- a/cmd.py
+++ b/cmd.py
@@ -99,9 +99,6 @@ class Commands(object):
     def get_public_node(self, args):
         return self.client.get_public_node(args.n)
     
-    def get_serial_number(self, args):
-        return binascii.hexlify(self.client.get_serial_number())
-
     def set_label(self, args):
         return self.client.apply_settings(label=args.label)
 
@@ -109,9 +106,14 @@ class Commands(object):
         return self.client.apply_settings(coin_shortcut=args.coin_shortcut)
 
     def load_device(self, args):
-        seed = ' '.join(args.seed)
+        if not args.mnemonic and not args.xprv:
+            raise Exception("Please provide mnemonic or xprv")
 
-        return self.client.load_device(seed, args.pin) 
+        if args.mnemonic:
+            mnemonic = ' '.join(args.mnemonic)
+            return self.client.load_device_by_mnemonic(mnemonic, args.pin, args.passphrase_protection)
+
+        return self.client.load_device_by_xprv(args.xprv, args.pin, args.passphrase_protection)
 
     def sign_message(self, args):
         return self.client.sign_message(args.n, args.message)
@@ -134,7 +136,6 @@ class Commands(object):
     get_address.help = 'Get bitcoin address in base58 encoding'
     get_entropy.help = 'Get example entropy'
     get_features.help = 'Retrieve device features and settings'
-    get_serial_number.help = 'Get device\'s unique identifier'
     get_public_node.help = 'Get public node of given path'
     set_label.help = 'Set new wallet label'
     set_coin.help = 'Switch device to another crypto currency'
@@ -166,8 +167,10 @@ class Commands(object):
     )
 
     load_device.arguments = (
-        (('-s', '--seed'), {'type': str, 'nargs': '+'}),
-        (('-n', '--pin'), {'type': str, 'default': ''}),
+        (('-m', '--mnemonic'), {'type': str, 'nargs': '+'}),
+        (('-x', '--xprv'), {'type': str}),
+        (('-p', '--pin'), {'type': str, 'default': ''}),
+        (('-r', '--passphrase-protection'), {'action': 'store_true', 'default': False}),
     )
 
     sign_message.arguments = (
diff --git a/tests/common.py b/tests/common.py
index 67367ab4b..9cd60e43e 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -3,7 +3,6 @@ import config
 
 from trezorlib.client import TrezorClient
 from trezorlib.debuglink import DebugLink
-from trezorlib import proto
 
 class TrezorTest(unittest.TestCase):
     def setUp(self):
@@ -19,7 +18,7 @@ class TrezorTest(unittest.TestCase):
         self.client.setup_debuglink(button=True, pin_correct=True)
         
         self.client.load_device(
-            seed=self.mnemonic1,
+            mnemonic=self.mnemonic1,
             pin=self.pin1)
 
         self.client.apply_settings(label='unit testing', coin_shortcut='BTC', language='english')
diff --git a/tests/test_basic.py b/tests/test_basic.py
index e25a47951..cfb61e9d0 100644
--- a/tests/test_basic.py
+++ b/tests/test_basic.py
@@ -1,7 +1,7 @@
 import unittest
 import common
 
-from trezorlib import proto
+from trezorlib import messages_pb2 as messages
 
 '''
     TODO:
@@ -14,16 +14,16 @@ from trezorlib import proto
 
 class TestBasic(common.TrezorTest):           
     def test_features(self):
-        features = self.client.call(proto.Initialize())
+        features = self.client.call(messages.Initialize())
         
         # Result is the same as reported by BitkeyClient class
         self.assertEqual(features, self.client.features)
          
     def test_ping(self):
-        ping = self.client.call(proto.Ping(message='ahoj!'))
+        ping = self.client.call(messages.Ping(message='ahoj!'))
         
         # Ping results in Success(message='Ahoj!')
-        self.assertEqual(ping, proto.Success(message='ahoj!'))
+        self.assertEqual(ping, messages.Success(message='ahoj!'))
         
     def test_uuid(self):
         uuid1 = self.client.get_device_id()
diff --git a/trezorlib/client.py b/trezorlib/client.py
index 22c2375ba..d3440d663 100644
--- a/trezorlib/client.py
+++ b/trezorlib/client.py
@@ -2,6 +2,7 @@ import os
 import time
 
 import ckd_public
+import tools
 import messages_pb2 as proto
 import types_pb2 as types
 
@@ -22,6 +23,8 @@ class CallException(Exception):
 class PinException(CallException):
     pass
 
+PRIME_DERIVATION_FLAG = 0x80000000
+
 class TrezorClient(object):
     
     def __init__(self, transport, debuglink=None, 
@@ -39,6 +42,10 @@ class TrezorClient(object):
     
     def _get_local_entropy(self):
         return os.urandom(32)
+
+    def _convert_prime(self, n):
+        # Convert minus signs to uint32 with flag
+        return [ int(abs(x) | PRIME_DERIVATION_FLAG) if x < 0 else x for x in n ]
         
     def init_device(self):
         self.features = self.call(proto.Initialize())
@@ -49,10 +56,11 @@ class TrezorClient(object):
             self.debuglink.transport.close()
 
     def get_public_node(self, n):
-        # print self.bip32_ckd(self.call(proto.GetPublicKey(address_n=n)).node, [2, ])
+        n = self._convert_prime(n)
         return self.call(proto.GetPublicKey(address_n=n)).node
         
     def get_address(self, n):
+        n = self._convert_prime(n)
         return self.call(proto.GetAddress(address_n=n)).address
         
     def get_entropy(self, size):
@@ -139,6 +147,7 @@ class TrezorClient(object):
         return resp
 
     def sign_message(self, n, message):
+        n = self._convert_prime(n)
         return self.call(proto.SignMessage(address_n=n, message=message))
 
     def verify_message(self, address, signature, message):
@@ -266,8 +275,42 @@ class TrezorClient(object):
         self.init_device()
         return isinstance(resp, proto.Success)
     
-    def load_device(self, seed, pin):        
-        resp = self.call(proto.LoadDevice(seed=seed, pin=pin))
+    def load_device_by_mnemonic(self, mnemonic, pin, passphrase_protection):
+        resp = self.call(proto.LoadDevice(mnemonic=mnemonic, pin=pin, passphrase_protection=passphrase_protection))
+        self.init_device()
+        return isinstance(resp, proto.Success)
+
+    def load_device_by_xprv(self, xprv, pin, passphrase_protection):
+        if xprv[0:4] not in ('xprv', 'tprv'):
+            raise Exception("Unknown type of xprv")
+
+        if len(xprv) < 100 and len(xprv) > 112:
+            raise Exception("Invalid length of xprv")
+
+        node = types.HDNodeType()
+        data = tools.b58decode(xprv, None).encode('hex')
+
+        if data[90:92] != '00':
+            raise Exception("Contain invalid private key")
+
+        # version 0488ade4
+        # depth 00
+        # fingerprint 00000000
+        # child_num 00000000
+        # chaincode 873dff81c02f525623fd1fe5167eac3a55a049de3d314bb42ee227ffed37d508
+        # privkey   00e8f32e723decf4051aefac8e2c93c9c5b214313817cdb01a1494b917c8436b35
+        # wtf is this? e77e9d71
+
+        node.version = int(data[0:8], 16)
+        node.depth = int(data[8:10], 16)
+        node.fingerprint = int(data[10:18], 16)
+        node.child_num = int(data[18:26], 16)
+        node.chain_code = data[26:90].decode('hex')
+        node.private_key = data[92:156].decode('hex')  # skip 0x00 indicating privkey
+        print 'wtf is this?', len(data[156:])
+        # FIXME
+        
+        resp = self.call(proto.LoadDevice(node=node, pin=pin, passphrase_protection=passphrase_protection))
         self.init_device()
         return isinstance(resp, proto.Success)