diff --git a/src/trezor/messages/Address.py b/src/trezor/messages/Address.py
index 712e6bd84..c04a40a28 100644
--- a/src/trezor/messages/Address.py
+++ b/src/trezor/messages/Address.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Address')
-t.wire_type = const(30)
-t.add_field(1, 'address', p.UnicodeType, flags=p.FLAG_REQUIRED)
-Address = t
+
+class Address(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UnicodeType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 30
diff --git a/src/trezor/messages/ApplySettings.py b/src/trezor/messages/ApplySettings.py
index 094314876..425103833 100644
--- a/src/trezor/messages/ApplySettings.py
+++ b/src/trezor/messages/ApplySettings.py
@@ -1,10 +1,12 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ApplySettings')
-t.wire_type = const(25)
-t.add_field(1, 'language', p.UnicodeType)
-t.add_field(2, 'label', p.UnicodeType)
-t.add_field(3, 'use_passphrase', p.BoolType)
-t.add_field(4, 'homescreen', p.BytesType)
-ApplySettings = t
+
+class ApplySettings(p.MessageType):
+    FIELDS = {
+        1: ('language', p.UnicodeType, 0),
+        2: ('label', p.UnicodeType, 0),
+        3: ('use_passphrase', p.BoolType, 0),
+        4: ('homescreen', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 25
diff --git a/src/trezor/messages/ButtonAck.py b/src/trezor/messages/ButtonAck.py
index 581176cdd..c23d363f8 100644
--- a/src/trezor/messages/ButtonAck.py
+++ b/src/trezor/messages/ButtonAck.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ButtonAck')
-t.wire_type = const(27)
-ButtonAck = t
+
+class ButtonAck(p.MessageType):
+    MESSAGE_WIRE_TYPE = 27
diff --git a/src/trezor/messages/ButtonRequest.py b/src/trezor/messages/ButtonRequest.py
index de8446acd..f3f0c0157 100644
--- a/src/trezor/messages/ButtonRequest.py
+++ b/src/trezor/messages/ButtonRequest.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ButtonRequest')
-t.wire_type = const(26)
-t.add_field(1, 'code', p.UVarintType)
-t.add_field(2, 'data', p.UnicodeType)
-ButtonRequest = t
+
+class ButtonRequest(p.MessageType):
+    FIELDS = {
+        1: ('code', p.UVarintType, 0),
+        2: ('data', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 26
diff --git a/src/trezor/messages/Cancel.py b/src/trezor/messages/Cancel.py
index cb7fbd530..1effb5d5f 100644
--- a/src/trezor/messages/Cancel.py
+++ b/src/trezor/messages/Cancel.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Cancel')
-t.wire_type = const(20)
-Cancel = t
+
+class Cancel(p.MessageType):
+    MESSAGE_WIRE_TYPE = 20
diff --git a/src/trezor/messages/ChangePin.py b/src/trezor/messages/ChangePin.py
index 2411e6938..d4f1162b9 100644
--- a/src/trezor/messages/ChangePin.py
+++ b/src/trezor/messages/ChangePin.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ChangePin')
-t.wire_type = const(4)
-t.add_field(1, 'remove', p.BoolType)
-ChangePin = t
+
+class ChangePin(p.MessageType):
+    FIELDS = {
+        1: ('remove', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 4
diff --git a/src/trezor/messages/CipherKeyValue.py b/src/trezor/messages/CipherKeyValue.py
index 381b77d5e..24cf26be4 100644
--- a/src/trezor/messages/CipherKeyValue.py
+++ b/src/trezor/messages/CipherKeyValue.py
@@ -1,13 +1,15 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('CipherKeyValue')
-t.wire_type = const(23)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'key', p.UnicodeType)
-t.add_field(3, 'value', p.BytesType)
-t.add_field(4, 'encrypt', p.BoolType)
-t.add_field(5, 'ask_on_encrypt', p.BoolType)
-t.add_field(6, 'ask_on_decrypt', p.BoolType)
-t.add_field(7, 'iv', p.BytesType)
-CipherKeyValue = t
+
+class CipherKeyValue(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('key', p.UnicodeType, 0),
+        3: ('value', p.BytesType, 0),
+        4: ('encrypt', p.BoolType, 0),
+        5: ('ask_on_encrypt', p.BoolType, 0),
+        6: ('ask_on_decrypt', p.BoolType, 0),
+        7: ('iv', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 23
diff --git a/src/trezor/messages/CipheredKeyValue.py b/src/trezor/messages/CipheredKeyValue.py
index 959025f95..86fc46d97 100644
--- a/src/trezor/messages/CipheredKeyValue.py
+++ b/src/trezor/messages/CipheredKeyValue.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('CipheredKeyValue')
-t.wire_type = const(48)
-t.add_field(1, 'value', p.BytesType)
-CipheredKeyValue = t
+
+class CipheredKeyValue(p.MessageType):
+    FIELDS = {
+        1: ('value', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 48
diff --git a/src/trezor/messages/ClearSession.py b/src/trezor/messages/ClearSession.py
index fd723b0a3..a80d802d8 100644
--- a/src/trezor/messages/ClearSession.py
+++ b/src/trezor/messages/ClearSession.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ClearSession')
-t.wire_type = const(24)
-ClearSession = t
+
+class ClearSession(p.MessageType):
+    MESSAGE_WIRE_TYPE = 24
diff --git a/src/trezor/messages/CoinType.py b/src/trezor/messages/CoinType.py
index a0bc65788..40d7aaf19 100644
--- a/src/trezor/messages/CoinType.py
+++ b/src/trezor/messages/CoinType.py
@@ -1,13 +1,15 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('CoinType')
-t.add_field(1, 'coin_name', p.UnicodeType)
-t.add_field(2, 'coin_shortcut', p.UnicodeType)
-t.add_field(3, 'address_type', p.UVarintType, default=0)
-t.add_field(4, 'maxfee_kb', p.UVarintType)
-t.add_field(5, 'address_type_p2sh', p.UVarintType, default=5)
-t.add_field(6, 'address_type_p2wpkh', p.UVarintType, default=6)
-t.add_field(7, 'address_type_p2wsh', p.UVarintType, default=10)
-t.add_field(8, 'signed_message_header', p.UnicodeType)
-CoinType = t
+
+class CoinType(p.MessageType):
+    FIELDS = {
+        1: ('coin_name', p.UnicodeType, 0),
+        2: ('coin_shortcut', p.UnicodeType, 0),
+        3: ('address_type', p.UVarintType, 0), # default=0
+        4: ('maxfee_kb', p.UVarintType, 0),
+        5: ('address_type_p2sh', p.UVarintType, 0), # default=5
+        6: ('address_type_p2wpkh', p.UVarintType, 0), # default=6
+        7: ('address_type_p2wsh', p.UVarintType, 0), # default=10
+        8: ('signed_message_header', p.UnicodeType, 0),
+    }
diff --git a/src/trezor/messages/DebugLinkDecision.py b/src/trezor/messages/DebugLinkDecision.py
index 10ff15e3a..2c4ebc3d0 100644
--- a/src/trezor/messages/DebugLinkDecision.py
+++ b/src/trezor/messages/DebugLinkDecision.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkDecision')
-t.wire_type = const(100)
-t.add_field(1, 'yes_no', p.BoolType, flags=p.FLAG_REQUIRED)
-DebugLinkDecision = t
+
+class DebugLinkDecision(p.MessageType):
+    FIELDS = {
+        1: ('yes_no', p.BoolType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 100
diff --git a/src/trezor/messages/DebugLinkFlashErase.py b/src/trezor/messages/DebugLinkFlashErase.py
index 9aedfee77..6751cc043 100644
--- a/src/trezor/messages/DebugLinkFlashErase.py
+++ b/src/trezor/messages/DebugLinkFlashErase.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkFlashErase')
-t.wire_type = const(113)
-t.add_field(1, 'sector', p.UVarintType)
-DebugLinkFlashErase = t
+
+class DebugLinkFlashErase(p.MessageType):
+    FIELDS = {
+        1: ('sector', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 113
diff --git a/src/trezor/messages/DebugLinkGetState.py b/src/trezor/messages/DebugLinkGetState.py
index d772bad56..26615584f 100644
--- a/src/trezor/messages/DebugLinkGetState.py
+++ b/src/trezor/messages/DebugLinkGetState.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkGetState')
-t.wire_type = const(101)
-DebugLinkGetState = t
+
+class DebugLinkGetState(p.MessageType):
+    MESSAGE_WIRE_TYPE = 101
diff --git a/src/trezor/messages/DebugLinkLog.py b/src/trezor/messages/DebugLinkLog.py
index dde2eecce..0b4707b2a 100644
--- a/src/trezor/messages/DebugLinkLog.py
+++ b/src/trezor/messages/DebugLinkLog.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkLog')
-t.wire_type = const(104)
-t.add_field(1, 'level', p.UVarintType)
-t.add_field(2, 'bucket', p.UnicodeType)
-t.add_field(3, 'text', p.UnicodeType)
-DebugLinkLog = t
+
+class DebugLinkLog(p.MessageType):
+    FIELDS = {
+        1: ('level', p.UVarintType, 0),
+        2: ('bucket', p.UnicodeType, 0),
+        3: ('text', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 104
diff --git a/src/trezor/messages/DebugLinkMemory.py b/src/trezor/messages/DebugLinkMemory.py
index 40d27b20e..fd2227c67 100644
--- a/src/trezor/messages/DebugLinkMemory.py
+++ b/src/trezor/messages/DebugLinkMemory.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkMemory')
-t.wire_type = const(111)
-t.add_field(1, 'memory', p.BytesType)
-DebugLinkMemory = t
+
+class DebugLinkMemory(p.MessageType):
+    FIELDS = {
+        1: ('memory', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 111
diff --git a/src/trezor/messages/DebugLinkMemoryRead.py b/src/trezor/messages/DebugLinkMemoryRead.py
index c991bd978..25954e421 100644
--- a/src/trezor/messages/DebugLinkMemoryRead.py
+++ b/src/trezor/messages/DebugLinkMemoryRead.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkMemoryRead')
-t.wire_type = const(110)
-t.add_field(1, 'address', p.UVarintType)
-t.add_field(2, 'length', p.UVarintType)
-DebugLinkMemoryRead = t
+
+class DebugLinkMemoryRead(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UVarintType, 0),
+        2: ('length', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 110
diff --git a/src/trezor/messages/DebugLinkMemoryWrite.py b/src/trezor/messages/DebugLinkMemoryWrite.py
index 9ab2b0b27..d3b6822ae 100644
--- a/src/trezor/messages/DebugLinkMemoryWrite.py
+++ b/src/trezor/messages/DebugLinkMemoryWrite.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkMemoryWrite')
-t.wire_type = const(112)
-t.add_field(1, 'address', p.UVarintType)
-t.add_field(2, 'memory', p.BytesType)
-t.add_field(3, 'flash', p.BoolType)
-DebugLinkMemoryWrite = t
+
+class DebugLinkMemoryWrite(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UVarintType, 0),
+        2: ('memory', p.BytesType, 0),
+        3: ('flash', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 112
diff --git a/src/trezor/messages/DebugLinkState.py b/src/trezor/messages/DebugLinkState.py
index 513b09af1..16ed8d1ba 100644
--- a/src/trezor/messages/DebugLinkState.py
+++ b/src/trezor/messages/DebugLinkState.py
@@ -2,16 +2,18 @@
 import protobuf as p
 from micropython import const
 from .HDNodeType import HDNodeType
-t = p.MessageType('DebugLinkState')
-t.wire_type = const(102)
-t.add_field(1, 'layout', p.BytesType)
-t.add_field(2, 'pin', p.UnicodeType)
-t.add_field(3, 'matrix', p.UnicodeType)
-t.add_field(4, 'mnemonic', p.UnicodeType)
-t.add_field(5, 'node', p.EmbeddedMessage(HDNodeType))
-t.add_field(6, 'passphrase_protection', p.BoolType)
-t.add_field(7, 'reset_word', p.UnicodeType)
-t.add_field(8, 'reset_entropy', p.BytesType)
-t.add_field(9, 'recovery_fake_word', p.UnicodeType)
-t.add_field(10, 'recovery_word_pos', p.UVarintType)
-DebugLinkState = t
+
+class DebugLinkState(p.MessageType):
+    FIELDS = {
+        1: ('layout', p.BytesType, 0),
+        2: ('pin', p.UnicodeType, 0),
+        3: ('matrix', p.UnicodeType, 0),
+        4: ('mnemonic', p.UnicodeType, 0),
+        5: ('node', HDNodeType, 0),
+        6: ('passphrase_protection', p.BoolType, 0),
+        7: ('reset_word', p.UnicodeType, 0),
+        8: ('reset_entropy', p.BytesType, 0),
+        9: ('recovery_fake_word', p.UnicodeType, 0),
+        10: ('recovery_word_pos', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 102
diff --git a/src/trezor/messages/DebugLinkStop.py b/src/trezor/messages/DebugLinkStop.py
index 08bc06bf2..4b409c261 100644
--- a/src/trezor/messages/DebugLinkStop.py
+++ b/src/trezor/messages/DebugLinkStop.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DebugLinkStop')
-t.wire_type = const(103)
-DebugLinkStop = t
+
+class DebugLinkStop(p.MessageType):
+    MESSAGE_WIRE_TYPE = 103
diff --git a/src/trezor/messages/DecryptMessage.py b/src/trezor/messages/DecryptMessage.py
index 1c6302175..31df8c384 100644
--- a/src/trezor/messages/DecryptMessage.py
+++ b/src/trezor/messages/DecryptMessage.py
@@ -1,10 +1,12 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DecryptMessage')
-t.wire_type = const(51)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'nonce', p.BytesType)
-t.add_field(3, 'message', p.BytesType)
-t.add_field(4, 'hmac', p.BytesType)
-DecryptMessage = t
+
+class DecryptMessage(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('nonce', p.BytesType, 0),
+        3: ('message', p.BytesType, 0),
+        4: ('hmac', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 51
diff --git a/src/trezor/messages/DecryptedMessage.py b/src/trezor/messages/DecryptedMessage.py
index 18d8a4146..4a9d03568 100644
--- a/src/trezor/messages/DecryptedMessage.py
+++ b/src/trezor/messages/DecryptedMessage.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('DecryptedMessage')
-t.wire_type = const(52)
-t.add_field(1, 'message', p.BytesType)
-t.add_field(2, 'address', p.UnicodeType)
-DecryptedMessage = t
+
+class DecryptedMessage(p.MessageType):
+    FIELDS = {
+        1: ('message', p.BytesType, 0),
+        2: ('address', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 52
diff --git a/src/trezor/messages/ECDHSessionKey.py b/src/trezor/messages/ECDHSessionKey.py
index 2a5233940..18eac7493 100644
--- a/src/trezor/messages/ECDHSessionKey.py
+++ b/src/trezor/messages/ECDHSessionKey.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ECDHSessionKey')
-t.wire_type = const(62)
-t.add_field(1, 'session_key', p.BytesType)
-ECDHSessionKey = t
+
+class ECDHSessionKey(p.MessageType):
+    FIELDS = {
+        1: ('session_key', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 62
diff --git a/src/trezor/messages/EncryptMessage.py b/src/trezor/messages/EncryptMessage.py
index 03a33418e..21e8c2924 100644
--- a/src/trezor/messages/EncryptMessage.py
+++ b/src/trezor/messages/EncryptMessage.py
@@ -1,11 +1,13 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EncryptMessage')
-t.wire_type = const(49)
-t.add_field(1, 'pubkey', p.BytesType)
-t.add_field(2, 'message', p.BytesType)
-t.add_field(3, 'display_only', p.BoolType)
-t.add_field(4, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(5, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-EncryptMessage = t
+
+class EncryptMessage(p.MessageType):
+    FIELDS = {
+        1: ('pubkey', p.BytesType, 0),
+        2: ('message', p.BytesType, 0),
+        3: ('display_only', p.BoolType, 0),
+        4: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        5: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+    }
+    MESSAGE_WIRE_TYPE = 49
diff --git a/src/trezor/messages/EncryptedMessage.py b/src/trezor/messages/EncryptedMessage.py
index df96a6656..2b9a98147 100644
--- a/src/trezor/messages/EncryptedMessage.py
+++ b/src/trezor/messages/EncryptedMessage.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EncryptedMessage')
-t.wire_type = const(50)
-t.add_field(1, 'nonce', p.BytesType)
-t.add_field(2, 'message', p.BytesType)
-t.add_field(3, 'hmac', p.BytesType)
-EncryptedMessage = t
+
+class EncryptedMessage(p.MessageType):
+    FIELDS = {
+        1: ('nonce', p.BytesType, 0),
+        2: ('message', p.BytesType, 0),
+        3: ('hmac', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 50
diff --git a/src/trezor/messages/Entropy.py b/src/trezor/messages/Entropy.py
index 3d34c172c..3cae777ae 100644
--- a/src/trezor/messages/Entropy.py
+++ b/src/trezor/messages/Entropy.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Entropy')
-t.wire_type = const(10)
-t.add_field(1, 'entropy', p.BytesType, flags=p.FLAG_REQUIRED)
-Entropy = t
+
+class Entropy(p.MessageType):
+    FIELDS = {
+        1: ('entropy', p.BytesType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 10
diff --git a/src/trezor/messages/EntropyAck.py b/src/trezor/messages/EntropyAck.py
index 17ebc1317..3266be488 100644
--- a/src/trezor/messages/EntropyAck.py
+++ b/src/trezor/messages/EntropyAck.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EntropyAck')
-t.wire_type = const(36)
-t.add_field(1, 'entropy', p.BytesType)
-EntropyAck = t
+
+class EntropyAck(p.MessageType):
+    FIELDS = {
+        1: ('entropy', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 36
diff --git a/src/trezor/messages/EntropyRequest.py b/src/trezor/messages/EntropyRequest.py
index e51b85c6c..42bf91208 100644
--- a/src/trezor/messages/EntropyRequest.py
+++ b/src/trezor/messages/EntropyRequest.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EntropyRequest')
-t.wire_type = const(35)
-EntropyRequest = t
+
+class EntropyRequest(p.MessageType):
+    MESSAGE_WIRE_TYPE = 35
diff --git a/src/trezor/messages/EstimateTxSize.py b/src/trezor/messages/EstimateTxSize.py
index 020b8c35e..8b19b1d77 100644
--- a/src/trezor/messages/EstimateTxSize.py
+++ b/src/trezor/messages/EstimateTxSize.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EstimateTxSize')
-t.wire_type = const(43)
-t.add_field(1, 'outputs_count', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(2, 'inputs_count', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(3, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-EstimateTxSize = t
+
+class EstimateTxSize(p.MessageType):
+    FIELDS = {
+        1: ('outputs_count', p.UVarintType, 0), # required
+        2: ('inputs_count', p.UVarintType, 0), # required
+        3: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+    }
+    MESSAGE_WIRE_TYPE = 43
diff --git a/src/trezor/messages/EthereumAddress.py b/src/trezor/messages/EthereumAddress.py
index c8b1a6c93..43238f40f 100644
--- a/src/trezor/messages/EthereumAddress.py
+++ b/src/trezor/messages/EthereumAddress.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EthereumAddress')
-t.wire_type = const(57)
-t.add_field(1, 'address', p.BytesType, flags=p.FLAG_REQUIRED)
-EthereumAddress = t
+
+class EthereumAddress(p.MessageType):
+    FIELDS = {
+        1: ('address', p.BytesType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 57
diff --git a/src/trezor/messages/EthereumGetAddress.py b/src/trezor/messages/EthereumGetAddress.py
index 62338dd42..31a31788f 100644
--- a/src/trezor/messages/EthereumGetAddress.py
+++ b/src/trezor/messages/EthereumGetAddress.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EthereumGetAddress')
-t.wire_type = const(56)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'show_display', p.BoolType)
-EthereumGetAddress = t
+
+class EthereumGetAddress(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('show_display', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 56
diff --git a/src/trezor/messages/EthereumSignTx.py b/src/trezor/messages/EthereumSignTx.py
index d11f76a4c..e154cf87d 100644
--- a/src/trezor/messages/EthereumSignTx.py
+++ b/src/trezor/messages/EthereumSignTx.py
@@ -1,14 +1,16 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EthereumSignTx')
-t.wire_type = const(58)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'nonce', p.BytesType)
-t.add_field(3, 'gas_price', p.BytesType)
-t.add_field(4, 'gas_limit', p.BytesType)
-t.add_field(5, 'to', p.BytesType)
-t.add_field(6, 'value', p.BytesType)
-t.add_field(7, 'data_initial_chunk', p.BytesType)
-t.add_field(8, 'data_length', p.UVarintType)
-EthereumSignTx = t
+
+class EthereumSignTx(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('nonce', p.BytesType, 0),
+        3: ('gas_price', p.BytesType, 0),
+        4: ('gas_limit', p.BytesType, 0),
+        5: ('to', p.BytesType, 0),
+        6: ('value', p.BytesType, 0),
+        7: ('data_initial_chunk', p.BytesType, 0),
+        8: ('data_length', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 58
diff --git a/src/trezor/messages/EthereumTxAck.py b/src/trezor/messages/EthereumTxAck.py
index d6fa37851..559a59fbd 100644
--- a/src/trezor/messages/EthereumTxAck.py
+++ b/src/trezor/messages/EthereumTxAck.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EthereumTxAck')
-t.wire_type = const(60)
-t.add_field(1, 'data_chunk', p.BytesType)
-EthereumTxAck = t
+
+class EthereumTxAck(p.MessageType):
+    FIELDS = {
+        1: ('data_chunk', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 60
diff --git a/src/trezor/messages/EthereumTxRequest.py b/src/trezor/messages/EthereumTxRequest.py
index 4f81f8013..af861cfa8 100644
--- a/src/trezor/messages/EthereumTxRequest.py
+++ b/src/trezor/messages/EthereumTxRequest.py
@@ -1,10 +1,12 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('EthereumTxRequest')
-t.wire_type = const(59)
-t.add_field(1, 'data_length', p.UVarintType)
-t.add_field(2, 'signature_v', p.UVarintType)
-t.add_field(3, 'signature_r', p.BytesType)
-t.add_field(4, 'signature_s', p.BytesType)
-EthereumTxRequest = t
+
+class EthereumTxRequest(p.MessageType):
+    FIELDS = {
+        1: ('data_length', p.UVarintType, 0),
+        2: ('signature_v', p.UVarintType, 0),
+        3: ('signature_r', p.BytesType, 0),
+        4: ('signature_s', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 59
diff --git a/src/trezor/messages/Failure.py b/src/trezor/messages/Failure.py
index 777d8fe6e..b285aa60d 100644
--- a/src/trezor/messages/Failure.py
+++ b/src/trezor/messages/Failure.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Failure')
-t.wire_type = const(3)
-t.add_field(1, 'code', p.UVarintType)
-t.add_field(2, 'message', p.UnicodeType)
-Failure = t
+
+class Failure(p.MessageType):
+    FIELDS = {
+        1: ('code', p.UVarintType, 0),
+        2: ('message', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 3
diff --git a/src/trezor/messages/Features.py b/src/trezor/messages/Features.py
index 751503c24..af5ebbeff 100644
--- a/src/trezor/messages/Features.py
+++ b/src/trezor/messages/Features.py
@@ -2,24 +2,26 @@
 import protobuf as p
 from micropython import const
 from .CoinType import CoinType
-t = p.MessageType('Features')
-t.wire_type = const(17)
-t.add_field(1, 'vendor', p.UnicodeType)
-t.add_field(2, 'major_version', p.UVarintType)
-t.add_field(3, 'minor_version', p.UVarintType)
-t.add_field(4, 'patch_version', p.UVarintType)
-t.add_field(5, 'bootloader_mode', p.BoolType)
-t.add_field(6, 'device_id', p.UnicodeType)
-t.add_field(7, 'pin_protection', p.BoolType)
-t.add_field(8, 'passphrase_protection', p.BoolType)
-t.add_field(9, 'language', p.UnicodeType)
-t.add_field(10, 'label', p.UnicodeType)
-t.add_field(11, 'coins', p.EmbeddedMessage(CoinType), flags=p.FLAG_REPEATED)
-t.add_field(12, 'initialized', p.BoolType)
-t.add_field(13, 'revision', p.BytesType)
-t.add_field(14, 'bootloader_hash', p.BytesType)
-t.add_field(15, 'imported', p.BoolType)
-t.add_field(16, 'pin_cached', p.BoolType)
-t.add_field(17, 'passphrase_cached', p.BoolType)
-t.add_field(18, 'firmware_present', p.BoolType)
-Features = t
+
+class Features(p.MessageType):
+    FIELDS = {
+        1: ('vendor', p.UnicodeType, 0),
+        2: ('major_version', p.UVarintType, 0),
+        3: ('minor_version', p.UVarintType, 0),
+        4: ('patch_version', p.UVarintType, 0),
+        5: ('bootloader_mode', p.BoolType, 0),
+        6: ('device_id', p.UnicodeType, 0),
+        7: ('pin_protection', p.BoolType, 0),
+        8: ('passphrase_protection', p.BoolType, 0),
+        9: ('language', p.UnicodeType, 0),
+        10: ('label', p.UnicodeType, 0),
+        11: ('coins', CoinType, p.FLAG_REPEATED),
+        12: ('initialized', p.BoolType, 0),
+        13: ('revision', p.BytesType, 0),
+        14: ('bootloader_hash', p.BytesType, 0),
+        15: ('imported', p.BoolType, 0),
+        16: ('pin_cached', p.BoolType, 0),
+        17: ('passphrase_cached', p.BoolType, 0),
+        18: ('firmware_present', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 17
diff --git a/src/trezor/messages/FirmwareErase.py b/src/trezor/messages/FirmwareErase.py
index e0609a380..4ec469f5b 100644
--- a/src/trezor/messages/FirmwareErase.py
+++ b/src/trezor/messages/FirmwareErase.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('FirmwareErase')
-t.wire_type = const(6)
-FirmwareErase = t
+
+class FirmwareErase(p.MessageType):
+    MESSAGE_WIRE_TYPE = 6
diff --git a/src/trezor/messages/FirmwareUpload.py b/src/trezor/messages/FirmwareUpload.py
index cb5f03254..2e53a2f36 100644
--- a/src/trezor/messages/FirmwareUpload.py
+++ b/src/trezor/messages/FirmwareUpload.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('FirmwareUpload')
-t.wire_type = const(7)
-t.add_field(1, 'payload', p.BytesType, flags=p.FLAG_REQUIRED)
-FirmwareUpload = t
+
+class FirmwareUpload(p.MessageType):
+    FIELDS = {
+        1: ('payload', p.BytesType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 7
diff --git a/src/trezor/messages/GetAddress.py b/src/trezor/messages/GetAddress.py
index bb7d11d1a..764ab2821 100644
--- a/src/trezor/messages/GetAddress.py
+++ b/src/trezor/messages/GetAddress.py
@@ -2,11 +2,13 @@
 import protobuf as p
 from micropython import const
 from .MultisigRedeemScriptType import MultisigRedeemScriptType
-t = p.MessageType('GetAddress')
-t.wire_type = const(29)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-t.add_field(3, 'show_display', p.BoolType)
-t.add_field(4, 'multisig', p.EmbeddedMessage(MultisigRedeemScriptType))
-t.add_field(5, 'script_type', p.UVarintType, default=0)
-GetAddress = t
+
+class GetAddress(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+        3: ('show_display', p.BoolType, 0),
+        4: ('multisig', MultisigRedeemScriptType, 0),
+        5: ('script_type', p.UVarintType, 0), # default=0
+    }
+    MESSAGE_WIRE_TYPE = 29
diff --git a/src/trezor/messages/GetECDHSessionKey.py b/src/trezor/messages/GetECDHSessionKey.py
index 0b112339f..2a7f7a130 100644
--- a/src/trezor/messages/GetECDHSessionKey.py
+++ b/src/trezor/messages/GetECDHSessionKey.py
@@ -2,9 +2,11 @@
 import protobuf as p
 from micropython import const
 from .IdentityType import IdentityType
-t = p.MessageType('GetECDHSessionKey')
-t.wire_type = const(61)
-t.add_field(1, 'identity', p.EmbeddedMessage(IdentityType))
-t.add_field(2, 'peer_public_key', p.BytesType)
-t.add_field(3, 'ecdsa_curve_name', p.UnicodeType)
-GetECDHSessionKey = t
+
+class GetECDHSessionKey(p.MessageType):
+    FIELDS = {
+        1: ('identity', IdentityType, 0),
+        2: ('peer_public_key', p.BytesType, 0),
+        3: ('ecdsa_curve_name', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 61
diff --git a/src/trezor/messages/GetEntropy.py b/src/trezor/messages/GetEntropy.py
index 9495a0597..78417e4a8 100644
--- a/src/trezor/messages/GetEntropy.py
+++ b/src/trezor/messages/GetEntropy.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('GetEntropy')
-t.wire_type = const(9)
-t.add_field(1, 'size', p.UVarintType, flags=p.FLAG_REQUIRED)
-GetEntropy = t
+
+class GetEntropy(p.MessageType):
+    FIELDS = {
+        1: ('size', p.UVarintType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 9
diff --git a/src/trezor/messages/GetFeatures.py b/src/trezor/messages/GetFeatures.py
index 02efc58ba..8fab4f121 100644
--- a/src/trezor/messages/GetFeatures.py
+++ b/src/trezor/messages/GetFeatures.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('GetFeatures')
-t.wire_type = const(55)
-GetFeatures = t
+
+class GetFeatures(p.MessageType):
+    MESSAGE_WIRE_TYPE = 55
diff --git a/src/trezor/messages/GetPublicKey.py b/src/trezor/messages/GetPublicKey.py
index bb78e3efa..adc19545e 100644
--- a/src/trezor/messages/GetPublicKey.py
+++ b/src/trezor/messages/GetPublicKey.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('GetPublicKey')
-t.wire_type = const(11)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'ecdsa_curve_name', p.UnicodeType)
-t.add_field(3, 'show_display', p.BoolType)
-GetPublicKey = t
+
+class GetPublicKey(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('ecdsa_curve_name', p.UnicodeType, 0),
+        3: ('show_display', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 11
diff --git a/src/trezor/messages/HDNodePathType.py b/src/trezor/messages/HDNodePathType.py
index 3afb9235c..d022f0096 100644
--- a/src/trezor/messages/HDNodePathType.py
+++ b/src/trezor/messages/HDNodePathType.py
@@ -2,7 +2,9 @@
 import protobuf as p
 from micropython import const
 from .HDNodeType import HDNodeType
-t = p.MessageType('HDNodePathType')
-t.add_field(1, 'node', p.EmbeddedMessage(HDNodeType), flags=p.FLAG_REQUIRED)
-t.add_field(2, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-HDNodePathType = t
+
+class HDNodePathType(p.MessageType):
+    FIELDS = {
+        1: ('node', HDNodeType, 0), # required
+        2: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+    }
diff --git a/src/trezor/messages/HDNodeType.py b/src/trezor/messages/HDNodeType.py
index 7e3ed0480..64e014756 100644
--- a/src/trezor/messages/HDNodeType.py
+++ b/src/trezor/messages/HDNodeType.py
@@ -1,11 +1,13 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('HDNodeType')
-t.add_field(1, 'depth', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(2, 'fingerprint', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(3, 'child_num', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(4, 'chain_code', p.BytesType, flags=p.FLAG_REQUIRED)
-t.add_field(5, 'private_key', p.BytesType)
-t.add_field(6, 'public_key', p.BytesType)
-HDNodeType = t
+
+class HDNodeType(p.MessageType):
+    FIELDS = {
+        1: ('depth', p.UVarintType, 0), # required
+        2: ('fingerprint', p.UVarintType, 0), # required
+        3: ('child_num', p.UVarintType, 0), # required
+        4: ('chain_code', p.BytesType, 0), # required
+        5: ('private_key', p.BytesType, 0),
+        6: ('public_key', p.BytesType, 0),
+    }
diff --git a/src/trezor/messages/IdentityType.py b/src/trezor/messages/IdentityType.py
index 5c3a2367e..a9b398e26 100644
--- a/src/trezor/messages/IdentityType.py
+++ b/src/trezor/messages/IdentityType.py
@@ -1,11 +1,13 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('IdentityType')
-t.add_field(1, 'proto', p.UnicodeType)
-t.add_field(2, 'user', p.UnicodeType)
-t.add_field(3, 'host', p.UnicodeType)
-t.add_field(4, 'port', p.UnicodeType)
-t.add_field(5, 'path', p.UnicodeType)
-t.add_field(6, 'index', p.UVarintType, default=0)
-IdentityType = t
+
+class IdentityType(p.MessageType):
+    FIELDS = {
+        1: ('proto', p.UnicodeType, 0),
+        2: ('user', p.UnicodeType, 0),
+        3: ('host', p.UnicodeType, 0),
+        4: ('port', p.UnicodeType, 0),
+        5: ('path', p.UnicodeType, 0),
+        6: ('index', p.UVarintType, 0), # default=0
+    }
diff --git a/src/trezor/messages/Initialize.py b/src/trezor/messages/Initialize.py
index c8de835d0..6929682dc 100644
--- a/src/trezor/messages/Initialize.py
+++ b/src/trezor/messages/Initialize.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Initialize')
-t.wire_type = const(0)
-Initialize = t
+
+class Initialize(p.MessageType):
+    MESSAGE_WIRE_TYPE = 0
diff --git a/src/trezor/messages/LoadDevice.py b/src/trezor/messages/LoadDevice.py
index f688d36d9..8be661ee0 100644
--- a/src/trezor/messages/LoadDevice.py
+++ b/src/trezor/messages/LoadDevice.py
@@ -2,13 +2,15 @@
 import protobuf as p
 from micropython import const
 from .HDNodeType import HDNodeType
-t = p.MessageType('LoadDevice')
-t.wire_type = const(13)
-t.add_field(1, 'mnemonic', p.UnicodeType)
-t.add_field(2, 'node', p.EmbeddedMessage(HDNodeType))
-t.add_field(3, 'pin', p.UnicodeType)
-t.add_field(4, 'passphrase_protection', p.BoolType)
-t.add_field(5, 'language', p.UnicodeType, default=u'english')
-t.add_field(6, 'label', p.UnicodeType)
-t.add_field(7, 'skip_checksum', p.BoolType)
-LoadDevice = t
+
+class LoadDevice(p.MessageType):
+    FIELDS = {
+        1: ('mnemonic', p.UnicodeType, 0),
+        2: ('node', HDNodeType, 0),
+        3: ('pin', p.UnicodeType, 0),
+        4: ('passphrase_protection', p.BoolType, 0),
+        5: ('language', p.UnicodeType, 0), # default=u'english'
+        6: ('label', p.UnicodeType, 0),
+        7: ('skip_checksum', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 13
diff --git a/src/trezor/messages/MessageSignature.py b/src/trezor/messages/MessageSignature.py
index 8de49fc5d..86da93832 100644
--- a/src/trezor/messages/MessageSignature.py
+++ b/src/trezor/messages/MessageSignature.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('MessageSignature')
-t.wire_type = const(40)
-t.add_field(1, 'address', p.UnicodeType)
-t.add_field(2, 'signature', p.BytesType)
-MessageSignature = t
+
+class MessageSignature(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UnicodeType, 0),
+        2: ('signature', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 40
diff --git a/src/trezor/messages/MultisigRedeemScriptType.py b/src/trezor/messages/MultisigRedeemScriptType.py
index d7e290f89..e3fad435e 100644
--- a/src/trezor/messages/MultisigRedeemScriptType.py
+++ b/src/trezor/messages/MultisigRedeemScriptType.py
@@ -2,8 +2,10 @@
 import protobuf as p
 from micropython import const
 from .HDNodePathType import HDNodePathType
-t = p.MessageType('MultisigRedeemScriptType')
-t.add_field(1, 'pubkeys', p.EmbeddedMessage(HDNodePathType), flags=p.FLAG_REPEATED)
-t.add_field(2, 'signatures', p.BytesType, flags=p.FLAG_REPEATED)
-t.add_field(3, 'm', p.UVarintType)
-MultisigRedeemScriptType = t
+
+class MultisigRedeemScriptType(p.MessageType):
+    FIELDS = {
+        1: ('pubkeys', HDNodePathType, p.FLAG_REPEATED),
+        2: ('signatures', p.BytesType, p.FLAG_REPEATED),
+        3: ('m', p.UVarintType, 0),
+    }
diff --git a/src/trezor/messages/PassphraseAck.py b/src/trezor/messages/PassphraseAck.py
index 55a157244..3f39ab574 100644
--- a/src/trezor/messages/PassphraseAck.py
+++ b/src/trezor/messages/PassphraseAck.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('PassphraseAck')
-t.wire_type = const(42)
-t.add_field(1, 'passphrase', p.UnicodeType, flags=p.FLAG_REQUIRED)
-PassphraseAck = t
+
+class PassphraseAck(p.MessageType):
+    FIELDS = {
+        1: ('passphrase', p.UnicodeType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 42
diff --git a/src/trezor/messages/PassphraseRequest.py b/src/trezor/messages/PassphraseRequest.py
index ea368e519..bfbb13b6f 100644
--- a/src/trezor/messages/PassphraseRequest.py
+++ b/src/trezor/messages/PassphraseRequest.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('PassphraseRequest')
-t.wire_type = const(41)
-PassphraseRequest = t
+
+class PassphraseRequest(p.MessageType):
+    MESSAGE_WIRE_TYPE = 41
diff --git a/src/trezor/messages/PinMatrixAck.py b/src/trezor/messages/PinMatrixAck.py
index a17981aeb..2a7961111 100644
--- a/src/trezor/messages/PinMatrixAck.py
+++ b/src/trezor/messages/PinMatrixAck.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('PinMatrixAck')
-t.wire_type = const(19)
-t.add_field(1, 'pin', p.UnicodeType, flags=p.FLAG_REQUIRED)
-PinMatrixAck = t
+
+class PinMatrixAck(p.MessageType):
+    FIELDS = {
+        1: ('pin', p.UnicodeType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 19
diff --git a/src/trezor/messages/PinMatrixRequest.py b/src/trezor/messages/PinMatrixRequest.py
index 29b599696..7b87504c9 100644
--- a/src/trezor/messages/PinMatrixRequest.py
+++ b/src/trezor/messages/PinMatrixRequest.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('PinMatrixRequest')
-t.wire_type = const(18)
-t.add_field(1, 'type', p.UVarintType)
-PinMatrixRequest = t
+
+class PinMatrixRequest(p.MessageType):
+    FIELDS = {
+        1: ('type', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 18
diff --git a/src/trezor/messages/Ping.py b/src/trezor/messages/Ping.py
index d17f2fc69..26c2fd8ea 100644
--- a/src/trezor/messages/Ping.py
+++ b/src/trezor/messages/Ping.py
@@ -1,10 +1,12 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Ping')
-t.wire_type = const(1)
-t.add_field(1, 'message', p.UnicodeType)
-t.add_field(2, 'button_protection', p.BoolType)
-t.add_field(3, 'pin_protection', p.BoolType)
-t.add_field(4, 'passphrase_protection', p.BoolType)
-Ping = t
+
+class Ping(p.MessageType):
+    FIELDS = {
+        1: ('message', p.UnicodeType, 0),
+        2: ('button_protection', p.BoolType, 0),
+        3: ('pin_protection', p.BoolType, 0),
+        4: ('passphrase_protection', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 1
diff --git a/src/trezor/messages/PublicKey.py b/src/trezor/messages/PublicKey.py
index d0ad4eb09..448463eca 100644
--- a/src/trezor/messages/PublicKey.py
+++ b/src/trezor/messages/PublicKey.py
@@ -2,8 +2,10 @@
 import protobuf as p
 from micropython import const
 from .HDNodeType import HDNodeType
-t = p.MessageType('PublicKey')
-t.wire_type = const(12)
-t.add_field(1, 'node', p.EmbeddedMessage(HDNodeType), flags=p.FLAG_REQUIRED)
-t.add_field(2, 'xpub', p.UnicodeType)
-PublicKey = t
+
+class PublicKey(p.MessageType):
+    FIELDS = {
+        1: ('node', HDNodeType, 0), # required
+        2: ('xpub', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 12
diff --git a/src/trezor/messages/RecoveryDevice.py b/src/trezor/messages/RecoveryDevice.py
index cb7b08361..a46e64531 100644
--- a/src/trezor/messages/RecoveryDevice.py
+++ b/src/trezor/messages/RecoveryDevice.py
@@ -1,12 +1,14 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('RecoveryDevice')
-t.wire_type = const(45)
-t.add_field(1, 'word_count', p.UVarintType)
-t.add_field(2, 'passphrase_protection', p.BoolType)
-t.add_field(3, 'pin_protection', p.BoolType)
-t.add_field(4, 'language', p.UnicodeType, default=u'english')
-t.add_field(5, 'label', p.UnicodeType)
-t.add_field(6, 'enforce_wordlist', p.BoolType)
-RecoveryDevice = t
+
+class RecoveryDevice(p.MessageType):
+    FIELDS = {
+        1: ('word_count', p.UVarintType, 0),
+        2: ('passphrase_protection', p.BoolType, 0),
+        3: ('pin_protection', p.BoolType, 0),
+        4: ('language', p.UnicodeType, 0), # default=u'english'
+        5: ('label', p.UnicodeType, 0),
+        6: ('enforce_wordlist', p.BoolType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 45
diff --git a/src/trezor/messages/ResetDevice.py b/src/trezor/messages/ResetDevice.py
index 1c9f1047c..73935487b 100644
--- a/src/trezor/messages/ResetDevice.py
+++ b/src/trezor/messages/ResetDevice.py
@@ -1,12 +1,14 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('ResetDevice')
-t.wire_type = const(14)
-t.add_field(1, 'display_random', p.BoolType)
-t.add_field(2, 'strength', p.UVarintType, default=256)
-t.add_field(3, 'passphrase_protection', p.BoolType)
-t.add_field(4, 'pin_protection', p.BoolType)
-t.add_field(5, 'language', p.UnicodeType, default=u'english')
-t.add_field(6, 'label', p.UnicodeType)
-ResetDevice = t
+
+class ResetDevice(p.MessageType):
+    FIELDS = {
+        1: ('display_random', p.BoolType, 0),
+        2: ('strength', p.UVarintType, 0), # default=256
+        3: ('passphrase_protection', p.BoolType, 0),
+        4: ('pin_protection', p.BoolType, 0),
+        5: ('language', p.UnicodeType, 0), # default=u'english'
+        6: ('label', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 14
diff --git a/src/trezor/messages/SetU2FCounter.py b/src/trezor/messages/SetU2FCounter.py
index 16dd27b05..993acb14b 100644
--- a/src/trezor/messages/SetU2FCounter.py
+++ b/src/trezor/messages/SetU2FCounter.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('SetU2FCounter')
-t.wire_type = const(63)
-t.add_field(1, 'u2f_counter', p.UVarintType)
-SetU2FCounter = t
+
+class SetU2FCounter(p.MessageType):
+    FIELDS = {
+        1: ('u2f_counter', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 63
diff --git a/src/trezor/messages/SignIdentity.py b/src/trezor/messages/SignIdentity.py
index 18f60074f..16a73adf2 100644
--- a/src/trezor/messages/SignIdentity.py
+++ b/src/trezor/messages/SignIdentity.py
@@ -2,10 +2,12 @@
 import protobuf as p
 from micropython import const
 from .IdentityType import IdentityType
-t = p.MessageType('SignIdentity')
-t.wire_type = const(53)
-t.add_field(1, 'identity', p.EmbeddedMessage(IdentityType))
-t.add_field(2, 'challenge_hidden', p.BytesType)
-t.add_field(3, 'challenge_visual', p.UnicodeType)
-t.add_field(4, 'ecdsa_curve_name', p.UnicodeType)
-SignIdentity = t
+
+class SignIdentity(p.MessageType):
+    FIELDS = {
+        1: ('identity', IdentityType, 0),
+        2: ('challenge_hidden', p.BytesType, 0),
+        3: ('challenge_visual', p.UnicodeType, 0),
+        4: ('ecdsa_curve_name', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 53
diff --git a/src/trezor/messages/SignMessage.py b/src/trezor/messages/SignMessage.py
index 22f8455e1..b2db7357f 100644
--- a/src/trezor/messages/SignMessage.py
+++ b/src/trezor/messages/SignMessage.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('SignMessage')
-t.wire_type = const(38)
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'message', p.BytesType, flags=p.FLAG_REQUIRED)
-t.add_field(3, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-SignMessage = t
+
+class SignMessage(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('message', p.BytesType, 0), # required
+        3: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+    }
+    MESSAGE_WIRE_TYPE = 38
diff --git a/src/trezor/messages/SignTx.py b/src/trezor/messages/SignTx.py
index d7d8617b3..2b6c7a339 100644
--- a/src/trezor/messages/SignTx.py
+++ b/src/trezor/messages/SignTx.py
@@ -1,11 +1,13 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('SignTx')
-t.wire_type = const(15)
-t.add_field(1, 'outputs_count', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(2, 'inputs_count', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(3, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-t.add_field(4, 'version', p.UVarintType, default=1)
-t.add_field(5, 'lock_time', p.UVarintType, default=0)
-SignTx = t
+
+class SignTx(p.MessageType):
+    FIELDS = {
+        1: ('outputs_count', p.UVarintType, 0), # required
+        2: ('inputs_count', p.UVarintType, 0), # required
+        3: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+        4: ('version', p.UVarintType, 0), # default=1
+        5: ('lock_time', p.UVarintType, 0), # default=0
+    }
+    MESSAGE_WIRE_TYPE = 15
diff --git a/src/trezor/messages/SignedIdentity.py b/src/trezor/messages/SignedIdentity.py
index bb751f33d..d5806a1b5 100644
--- a/src/trezor/messages/SignedIdentity.py
+++ b/src/trezor/messages/SignedIdentity.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('SignedIdentity')
-t.wire_type = const(54)
-t.add_field(1, 'address', p.UnicodeType)
-t.add_field(2, 'public_key', p.BytesType)
-t.add_field(3, 'signature', p.BytesType)
-SignedIdentity = t
+
+class SignedIdentity(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UnicodeType, 0),
+        2: ('public_key', p.BytesType, 0),
+        3: ('signature', p.BytesType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 54
diff --git a/src/trezor/messages/SimpleSignTx.py b/src/trezor/messages/SimpleSignTx.py
index fe595f1fc..65caf70c5 100644
--- a/src/trezor/messages/SimpleSignTx.py
+++ b/src/trezor/messages/SimpleSignTx.py
@@ -4,12 +4,14 @@ from micropython import const
 from .TxInputType import TxInputType
 from .TxOutputType import TxOutputType
 from .TransactionType import TransactionType
-t = p.MessageType('SimpleSignTx')
-t.wire_type = const(16)
-t.add_field(1, 'inputs', p.EmbeddedMessage(TxInputType), flags=p.FLAG_REPEATED)
-t.add_field(2, 'outputs', p.EmbeddedMessage(TxOutputType), flags=p.FLAG_REPEATED)
-t.add_field(3, 'transactions', p.EmbeddedMessage(TransactionType), flags=p.FLAG_REPEATED)
-t.add_field(4, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-t.add_field(5, 'version', p.UVarintType, default=1)
-t.add_field(6, 'lock_time', p.UVarintType, default=0)
-SimpleSignTx = t
+
+class SimpleSignTx(p.MessageType):
+    FIELDS = {
+        1: ('inputs', TxInputType, p.FLAG_REPEATED),
+        2: ('outputs', TxOutputType, p.FLAG_REPEATED),
+        3: ('transactions', TransactionType, p.FLAG_REPEATED),
+        4: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+        5: ('version', p.UVarintType, 0), # default=1
+        6: ('lock_time', p.UVarintType, 0), # default=0
+    }
+    MESSAGE_WIRE_TYPE = 16
diff --git a/src/trezor/messages/Storage.py b/src/trezor/messages/Storage.py
index ec5d2dd97..a577b57f8 100644
--- a/src/trezor/messages/Storage.py
+++ b/src/trezor/messages/Storage.py
@@ -2,16 +2,18 @@
 import protobuf as p
 from micropython import const
 from .HDNodeType import HDNodeType
-t = p.MessageType('Storage')
-t.add_field(1, 'version', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(2, 'node', p.EmbeddedMessage(HDNodeType))
-t.add_field(3, 'mnemonic', p.UnicodeType)
-t.add_field(4, 'passphrase_protection', p.BoolType)
-t.add_field(5, 'pin_failed_attempts', p.UVarintType)
-t.add_field(6, 'pin', p.UnicodeType)
-t.add_field(7, 'language', p.UnicodeType)
-t.add_field(8, 'label', p.UnicodeType)
-t.add_field(9, 'imported', p.BoolType)
-t.add_field(10, 'homescreen', p.BytesType)
-t.add_field(11, 'u2f_counter', p.UVarintType)
-Storage = t
+
+class Storage(p.MessageType):
+    FIELDS = {
+        1: ('version', p.UVarintType, 0), # required
+        2: ('node', HDNodeType, 0),
+        3: ('mnemonic', p.UnicodeType, 0),
+        4: ('passphrase_protection', p.BoolType, 0),
+        5: ('pin_failed_attempts', p.UVarintType, 0),
+        6: ('pin', p.UnicodeType, 0),
+        7: ('language', p.UnicodeType, 0),
+        8: ('label', p.UnicodeType, 0),
+        9: ('imported', p.BoolType, 0),
+        10: ('homescreen', p.BytesType, 0),
+        11: ('u2f_counter', p.UVarintType, 0),
+    }
diff --git a/src/trezor/messages/Success.py b/src/trezor/messages/Success.py
index ba55a5c7f..c39d80ad2 100644
--- a/src/trezor/messages/Success.py
+++ b/src/trezor/messages/Success.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('Success')
-t.wire_type = const(2)
-t.add_field(1, 'message', p.UnicodeType)
-Success = t
+
+class Success(p.MessageType):
+    FIELDS = {
+        1: ('message', p.UnicodeType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 2
diff --git a/src/trezor/messages/TransactionType.py b/src/trezor/messages/TransactionType.py
index 180c1893d..2ae18c7ed 100644
--- a/src/trezor/messages/TransactionType.py
+++ b/src/trezor/messages/TransactionType.py
@@ -4,14 +4,16 @@ from micropython import const
 from .TxInputType import TxInputType
 from .TxOutputBinType import TxOutputBinType
 from .TxOutputType import TxOutputType
-t = p.MessageType('TransactionType')
-t.add_field(1, 'version', p.UVarintType)
-t.add_field(2, 'inputs', p.EmbeddedMessage(TxInputType), flags=p.FLAG_REPEATED)
-t.add_field(3, 'bin_outputs', p.EmbeddedMessage(TxOutputBinType), flags=p.FLAG_REPEATED)
-t.add_field(4, 'lock_time', p.UVarintType)
-t.add_field(5, 'outputs', p.EmbeddedMessage(TxOutputType), flags=p.FLAG_REPEATED)
-t.add_field(6, 'inputs_cnt', p.UVarintType)
-t.add_field(7, 'outputs_cnt', p.UVarintType)
-t.add_field(8, 'extra_data', p.BytesType)
-t.add_field(9, 'extra_data_len', p.UVarintType)
-TransactionType = t
+
+class TransactionType(p.MessageType):
+    FIELDS = {
+        1: ('version', p.UVarintType, 0),
+        2: ('inputs', TxInputType, p.FLAG_REPEATED),
+        3: ('bin_outputs', TxOutputBinType, p.FLAG_REPEATED),
+        4: ('lock_time', p.UVarintType, 0),
+        5: ('outputs', TxOutputType, p.FLAG_REPEATED),
+        6: ('inputs_cnt', p.UVarintType, 0),
+        7: ('outputs_cnt', p.UVarintType, 0),
+        8: ('extra_data', p.BytesType, 0),
+        9: ('extra_data_len', p.UVarintType, 0),
+    }
diff --git a/src/trezor/messages/TxAck.py b/src/trezor/messages/TxAck.py
index bf7a32dcb..83d418a26 100644
--- a/src/trezor/messages/TxAck.py
+++ b/src/trezor/messages/TxAck.py
@@ -2,7 +2,9 @@
 import protobuf as p
 from micropython import const
 from .TransactionType import TransactionType
-t = p.MessageType('TxAck')
-t.wire_type = const(22)
-t.add_field(1, 'tx', p.EmbeddedMessage(TransactionType))
-TxAck = t
+
+class TxAck(p.MessageType):
+    FIELDS = {
+        1: ('tx', TransactionType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 22
diff --git a/src/trezor/messages/TxInputType.py b/src/trezor/messages/TxInputType.py
index 6917b9f2f..4038ef67d 100644
--- a/src/trezor/messages/TxInputType.py
+++ b/src/trezor/messages/TxInputType.py
@@ -2,13 +2,15 @@
 import protobuf as p
 from micropython import const
 from .MultisigRedeemScriptType import MultisigRedeemScriptType
-t = p.MessageType('TxInputType')
-t.add_field(1, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(2, 'prev_hash', p.BytesType, flags=p.FLAG_REQUIRED)
-t.add_field(3, 'prev_index', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(4, 'script_sig', p.BytesType)
-t.add_field(5, 'sequence', p.UVarintType, default=4294967295)
-t.add_field(6, 'script_type', p.UVarintType, default=0)
-t.add_field(7, 'multisig', p.EmbeddedMessage(MultisigRedeemScriptType))
-t.add_field(8, 'amount', p.UVarintType)
-TxInputType = t
+
+class TxInputType(p.MessageType):
+    FIELDS = {
+        1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        2: ('prev_hash', p.BytesType, 0), # required
+        3: ('prev_index', p.UVarintType, 0), # required
+        4: ('script_sig', p.BytesType, 0),
+        5: ('sequence', p.UVarintType, 0), # default=4294967295
+        6: ('script_type', p.UVarintType, 0), # default=0
+        7: ('multisig', MultisigRedeemScriptType, 0),
+        8: ('amount', p.UVarintType, 0),
+    }
diff --git a/src/trezor/messages/TxOutputBinType.py b/src/trezor/messages/TxOutputBinType.py
index 0ba47897c..3f7830ecf 100644
--- a/src/trezor/messages/TxOutputBinType.py
+++ b/src/trezor/messages/TxOutputBinType.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('TxOutputBinType')
-t.add_field(1, 'amount', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(2, 'script_pubkey', p.BytesType, flags=p.FLAG_REQUIRED)
-TxOutputBinType = t
+
+class TxOutputBinType(p.MessageType):
+    FIELDS = {
+        1: ('amount', p.UVarintType, 0), # required
+        2: ('script_pubkey', p.BytesType, 0), # required
+    }
diff --git a/src/trezor/messages/TxOutputType.py b/src/trezor/messages/TxOutputType.py
index d26faa2a1..05394fdb6 100644
--- a/src/trezor/messages/TxOutputType.py
+++ b/src/trezor/messages/TxOutputType.py
@@ -2,11 +2,13 @@
 import protobuf as p
 from micropython import const
 from .MultisigRedeemScriptType import MultisigRedeemScriptType
-t = p.MessageType('TxOutputType')
-t.add_field(1, 'address', p.UnicodeType)
-t.add_field(2, 'address_n', p.UVarintType, flags=p.FLAG_REPEATED)
-t.add_field(3, 'amount', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(4, 'script_type', p.UVarintType, flags=p.FLAG_REQUIRED)
-t.add_field(5, 'multisig', p.EmbeddedMessage(MultisigRedeemScriptType))
-t.add_field(6, 'op_return_data', p.BytesType)
-TxOutputType = t
+
+class TxOutputType(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UnicodeType, 0),
+        2: ('address_n', p.UVarintType, p.FLAG_REPEATED),
+        3: ('amount', p.UVarintType, 0), # required
+        4: ('script_type', p.UVarintType, 0), # required
+        5: ('multisig', MultisigRedeemScriptType, 0),
+        6: ('op_return_data', p.BytesType, 0),
+    }
diff --git a/src/trezor/messages/TxRequest.py b/src/trezor/messages/TxRequest.py
index 5eb4730fe..60e202409 100644
--- a/src/trezor/messages/TxRequest.py
+++ b/src/trezor/messages/TxRequest.py
@@ -3,9 +3,11 @@ import protobuf as p
 from micropython import const
 from .TxRequestDetailsType import TxRequestDetailsType
 from .TxRequestSerializedType import TxRequestSerializedType
-t = p.MessageType('TxRequest')
-t.wire_type = const(21)
-t.add_field(1, 'request_type', p.UVarintType)
-t.add_field(2, 'details', p.EmbeddedMessage(TxRequestDetailsType))
-t.add_field(3, 'serialized', p.EmbeddedMessage(TxRequestSerializedType))
-TxRequest = t
+
+class TxRequest(p.MessageType):
+    FIELDS = {
+        1: ('request_type', p.UVarintType, 0),
+        2: ('details', TxRequestDetailsType, 0),
+        3: ('serialized', TxRequestSerializedType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 21
diff --git a/src/trezor/messages/TxRequestDetailsType.py b/src/trezor/messages/TxRequestDetailsType.py
index e0cd05362..7aad5880c 100644
--- a/src/trezor/messages/TxRequestDetailsType.py
+++ b/src/trezor/messages/TxRequestDetailsType.py
@@ -1,9 +1,11 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('TxRequestDetailsType')
-t.add_field(1, 'request_index', p.UVarintType)
-t.add_field(2, 'tx_hash', p.BytesType)
-t.add_field(3, 'extra_data_len', p.UVarintType)
-t.add_field(4, 'extra_data_offset', p.UVarintType)
-TxRequestDetailsType = t
+
+class TxRequestDetailsType(p.MessageType):
+    FIELDS = {
+        1: ('request_index', p.UVarintType, 0),
+        2: ('tx_hash', p.BytesType, 0),
+        3: ('extra_data_len', p.UVarintType, 0),
+        4: ('extra_data_offset', p.UVarintType, 0),
+    }
diff --git a/src/trezor/messages/TxRequestSerializedType.py b/src/trezor/messages/TxRequestSerializedType.py
index 12efbebe9..5a700438e 100644
--- a/src/trezor/messages/TxRequestSerializedType.py
+++ b/src/trezor/messages/TxRequestSerializedType.py
@@ -1,8 +1,10 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('TxRequestSerializedType')
-t.add_field(1, 'signature_index', p.UVarintType)
-t.add_field(2, 'signature', p.BytesType)
-t.add_field(3, 'serialized_tx', p.BytesType)
-TxRequestSerializedType = t
+
+class TxRequestSerializedType(p.MessageType):
+    FIELDS = {
+        1: ('signature_index', p.UVarintType, 0),
+        2: ('signature', p.BytesType, 0),
+        3: ('serialized_tx', p.BytesType, 0),
+    }
diff --git a/src/trezor/messages/TxSize.py b/src/trezor/messages/TxSize.py
index 888814294..de9583e37 100644
--- a/src/trezor/messages/TxSize.py
+++ b/src/trezor/messages/TxSize.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('TxSize')
-t.wire_type = const(44)
-t.add_field(1, 'tx_size', p.UVarintType)
-TxSize = t
+
+class TxSize(p.MessageType):
+    FIELDS = {
+        1: ('tx_size', p.UVarintType, 0),
+    }
+    MESSAGE_WIRE_TYPE = 44
diff --git a/src/trezor/messages/VerifyMessage.py b/src/trezor/messages/VerifyMessage.py
index d62558970..90e3e6404 100644
--- a/src/trezor/messages/VerifyMessage.py
+++ b/src/trezor/messages/VerifyMessage.py
@@ -1,10 +1,12 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('VerifyMessage')
-t.wire_type = const(39)
-t.add_field(1, 'address', p.UnicodeType)
-t.add_field(2, 'signature', p.BytesType)
-t.add_field(3, 'message', p.BytesType)
-t.add_field(4, 'coin_name', p.UnicodeType, default=u'Bitcoin')
-VerifyMessage = t
+
+class VerifyMessage(p.MessageType):
+    FIELDS = {
+        1: ('address', p.UnicodeType, 0),
+        2: ('signature', p.BytesType, 0),
+        3: ('message', p.BytesType, 0),
+        4: ('coin_name', p.UnicodeType, 0), # default=u'Bitcoin'
+    }
+    MESSAGE_WIRE_TYPE = 39
diff --git a/src/trezor/messages/WipeDevice.py b/src/trezor/messages/WipeDevice.py
index 22535f4b1..36f197460 100644
--- a/src/trezor/messages/WipeDevice.py
+++ b/src/trezor/messages/WipeDevice.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('WipeDevice')
-t.wire_type = const(5)
-WipeDevice = t
+
+class WipeDevice(p.MessageType):
+    MESSAGE_WIRE_TYPE = 5
diff --git a/src/trezor/messages/WordAck.py b/src/trezor/messages/WordAck.py
index 377b67bbc..cf9ab65a2 100644
--- a/src/trezor/messages/WordAck.py
+++ b/src/trezor/messages/WordAck.py
@@ -1,7 +1,9 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('WordAck')
-t.wire_type = const(47)
-t.add_field(1, 'word', p.UnicodeType, flags=p.FLAG_REQUIRED)
-WordAck = t
+
+class WordAck(p.MessageType):
+    FIELDS = {
+        1: ('word', p.UnicodeType, 0), # required
+    }
+    MESSAGE_WIRE_TYPE = 47
diff --git a/src/trezor/messages/WordRequest.py b/src/trezor/messages/WordRequest.py
index 852f7494a..8ca75a7e2 100644
--- a/src/trezor/messages/WordRequest.py
+++ b/src/trezor/messages/WordRequest.py
@@ -1,6 +1,6 @@
 # Automatically generated by pb2py
 import protobuf as p
 from micropython import const
-t = p.MessageType('WordRequest')
-t.wire_type = const(46)
-WordRequest = t
+
+class WordRequest(p.MessageType):
+    MESSAGE_WIRE_TYPE = 46