diff --git a/Makefile b/Makefile
index a371b14c22..5dcee7bc32 100644
--- a/Makefile
+++ b/Makefile
@@ -47,6 +47,9 @@ test: ## run unit tests
 testpy: ## run selected unit tests from python-trezor
 	cd tests ; ./run_tests_python_trezor.sh
 
+pylint: ## run pylint on application sources
+	pylint --rcfile=pylint.rc -E $(shell find src -name *.py)
+
 ## build commands:
 
 build: build_boardloader build_bootloader build_firmware build_unix build_cross ## build all
diff --git a/mocks/micropython.py b/mocks/micropython.py
index 436f58cb2b..0fac10569a 100644
--- a/mocks/micropython.py
+++ b/mocks/micropython.py
@@ -1,5 +1,5 @@
 def const(c):
-    pass
+    return c
 
 def mem_info(verbose=None):
     pass
diff --git a/mocks/ubinascii.py b/mocks/ubinascii.py
index 79280af45d..7dd47dc54e 100644
--- a/mocks/ubinascii.py
+++ b/mocks/ubinascii.py
@@ -1,11 +1,14 @@
 def hexlify(data, sep=None):
-    pass
+    return 0
 
 def unhexlify(data):
-    pass
+    return 0
 
 def a2b_base64(data):
-    pass
+    return 0
 
 def b2a_base64(data):
-    pass
+    return 0
+
+def crc32(data, crc=None):
+    return 0
diff --git a/mocks/uctypes.py b/mocks/uctypes.py
new file mode 100644
index 0000000000..dac719a6d8
--- /dev/null
+++ b/mocks/uctypes.py
@@ -0,0 +1,37 @@
+ARRAY = 0
+NATIVE = 0
+LITTLE_ENDIAN = 0
+BIG_ENDIAN = 0
+VOID = 0
+UINT8 = 0
+INT8 = 0
+UINT16 = 0
+INT16 = 0
+UINT32 = 0
+INT32 = 0
+UINT64 = 0
+INT64 = 0
+BFUINT8 = 0
+BFINT8 = 0
+BFUINT16 = 0
+BFINT16 = 0
+BFUINT32 = 0
+BFINT32 = 0
+BF_POS = 0
+BF_LEN = 0
+FLOAT32 = 0
+
+def struct(addr, descriptor, layout_type=NATIVE):
+    return 0
+
+def sizeof(struct):
+    return 0
+
+def addressof(obj):
+    return 0
+
+def bytes_at(addr, size):
+    return 0
+
+def bytearray_at(addr, size):
+    return 0
diff --git a/mocks/ustruct.py b/mocks/ustruct.py
index aae1e50ff5..d98dff1796 100644
--- a/mocks/ustruct.py
+++ b/mocks/ustruct.py
@@ -1,14 +1,14 @@
 def calcsize(fmt):
-    pass
+    return 0
 
 def pack(fmt, *args):
-    pass
+    return 0
 
 def pack_info(fmt, buffer, offset, *args):
-    pass
+    return 0
 
 def unpack(fmt, data):
-    pass
+    return 0
 
 def unpack_from(fmt, data, offset=0):
-    pass
+    return 0
diff --git a/mocks/utime.py b/mocks/utime.py
index ad30d7cf78..66c2c48cfc 100644
--- a/mocks/utime.py
+++ b/mocks/utime.py
@@ -1,11 +1,11 @@
 def localtime(secs=None):
-    pass
+    return 0
 
 def ticks_ms():
-    pass
+    return 0
 
 def mktime():
-    pass
+    return 0
 
 def sleep(seconds):
     pass
@@ -17,16 +17,19 @@ def sleep_us(us):
     pass
 
 def ticks_ms():
-    pass
+    return 0
 
 def ticks_us():
-    pass
+    return 0
 
 def ticks_cpu():
-    pass
+    return 0
+
+def ticks_add(ticks_in, delta_in):
+    return 0
 
 def ticks_diff(old, new):
-    pass
+    return 0
 
 def time():
-    pass
+    return 0
diff --git a/pylint.rc b/pylint.rc
new file mode 100644
index 0000000000..44ad8e37cb
--- /dev/null
+++ b/pylint.rc
@@ -0,0 +1,2 @@
+[MASTER]
+init-hook='sys.path.insert(0, "mocks")'
diff --git a/src/apps/fido_u2f/__init__.py b/src/apps/fido_u2f/__init__.py
index 4354203fa4..c3d5107d9d 100644
--- a/src/apps/fido_u2f/__init__.py
+++ b/src/apps/fido_u2f/__init__.py
@@ -1,3 +1,5 @@
+from micropython import const
+
 import uctypes
 import ustruct
 import utime
diff --git a/src/main.py b/src/main.py
index 0bc5100e2e..a1537964f4 100644
--- a/src/main.py
+++ b/src/main.py
@@ -1,3 +1,5 @@
+from micropython import const
+
 import trezor.main
 from trezor import msg
 from trezor import ui
diff --git a/src/trezor/messages/Address.py b/src/trezor/messages/Address.py
index fc361ab865..5ba296d0ab 100644
--- a/src/trezor/messages/Address.py
+++ b/src/trezor/messages/Address.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Address(p.MessageType):
diff --git a/src/trezor/messages/ApplySettings.py b/src/trezor/messages/ApplySettings.py
index 83a85e539d..9c47fff330 100644
--- a/src/trezor/messages/ApplySettings.py
+++ b/src/trezor/messages/ApplySettings.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ApplySettings(p.MessageType):
diff --git a/src/trezor/messages/ButtonAck.py b/src/trezor/messages/ButtonAck.py
index f09c192e54..0d13f1b1b7 100644
--- a/src/trezor/messages/ButtonAck.py
+++ b/src/trezor/messages/ButtonAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ButtonAck(p.MessageType):
diff --git a/src/trezor/messages/ButtonRequest.py b/src/trezor/messages/ButtonRequest.py
index 07a1ebc3e3..a53d781f8b 100644
--- a/src/trezor/messages/ButtonRequest.py
+++ b/src/trezor/messages/ButtonRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ButtonRequest(p.MessageType):
diff --git a/src/trezor/messages/ButtonRequestType.py b/src/trezor/messages/ButtonRequestType.py
index 779d4f63d6..f6b799d4c3 100644
--- a/src/trezor/messages/ButtonRequestType.py
+++ b/src/trezor/messages/ButtonRequestType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 Other = const(1)
 FeeOverThreshold = const(2)
 ConfirmOutput = const(3)
diff --git a/src/trezor/messages/Cancel.py b/src/trezor/messages/Cancel.py
index bf2aa32e08..cb7bf9e166 100644
--- a/src/trezor/messages/Cancel.py
+++ b/src/trezor/messages/Cancel.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Cancel(p.MessageType):
diff --git a/src/trezor/messages/ChangePin.py b/src/trezor/messages/ChangePin.py
index fd6e37795d..4201251ae4 100644
--- a/src/trezor/messages/ChangePin.py
+++ b/src/trezor/messages/ChangePin.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ChangePin(p.MessageType):
diff --git a/src/trezor/messages/CipherKeyValue.py b/src/trezor/messages/CipherKeyValue.py
index 58fa5debb8..762cf65f54 100644
--- a/src/trezor/messages/CipherKeyValue.py
+++ b/src/trezor/messages/CipherKeyValue.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class CipherKeyValue(p.MessageType):
diff --git a/src/trezor/messages/CipheredKeyValue.py b/src/trezor/messages/CipheredKeyValue.py
index b4dfeeb781..ec4edc43ba 100644
--- a/src/trezor/messages/CipheredKeyValue.py
+++ b/src/trezor/messages/CipheredKeyValue.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class CipheredKeyValue(p.MessageType):
diff --git a/src/trezor/messages/ClearSession.py b/src/trezor/messages/ClearSession.py
index 84fa334589..338c75ffe5 100644
--- a/src/trezor/messages/ClearSession.py
+++ b/src/trezor/messages/ClearSession.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ClearSession(p.MessageType):
diff --git a/src/trezor/messages/CoinType.py b/src/trezor/messages/CoinType.py
index 079fe5ff8d..ce7b95979c 100644
--- a/src/trezor/messages/CoinType.py
+++ b/src/trezor/messages/CoinType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class CoinType(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkDecision.py b/src/trezor/messages/DebugLinkDecision.py
index e57d513a3e..6257cabd3d 100644
--- a/src/trezor/messages/DebugLinkDecision.py
+++ b/src/trezor/messages/DebugLinkDecision.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkDecision(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkFlashErase.py b/src/trezor/messages/DebugLinkFlashErase.py
index f66d051836..9a7409a8b1 100644
--- a/src/trezor/messages/DebugLinkFlashErase.py
+++ b/src/trezor/messages/DebugLinkFlashErase.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkFlashErase(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkGetState.py b/src/trezor/messages/DebugLinkGetState.py
index 007e3a8ccd..8acabc81a0 100644
--- a/src/trezor/messages/DebugLinkGetState.py
+++ b/src/trezor/messages/DebugLinkGetState.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkGetState(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkLog.py b/src/trezor/messages/DebugLinkLog.py
index 3740807088..35a3f25235 100644
--- a/src/trezor/messages/DebugLinkLog.py
+++ b/src/trezor/messages/DebugLinkLog.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkLog(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkMemory.py b/src/trezor/messages/DebugLinkMemory.py
index 1f6efabcf7..2757d2fb3a 100644
--- a/src/trezor/messages/DebugLinkMemory.py
+++ b/src/trezor/messages/DebugLinkMemory.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkMemory(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkMemoryRead.py b/src/trezor/messages/DebugLinkMemoryRead.py
index 39179a1b09..27805c9c79 100644
--- a/src/trezor/messages/DebugLinkMemoryRead.py
+++ b/src/trezor/messages/DebugLinkMemoryRead.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkMemoryRead(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkMemoryWrite.py b/src/trezor/messages/DebugLinkMemoryWrite.py
index c53de2a598..bb525fbffd 100644
--- a/src/trezor/messages/DebugLinkMemoryWrite.py
+++ b/src/trezor/messages/DebugLinkMemoryWrite.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkMemoryWrite(p.MessageType):
diff --git a/src/trezor/messages/DebugLinkState.py b/src/trezor/messages/DebugLinkState.py
index 8adf128bf7..a2e265d452 100644
--- a/src/trezor/messages/DebugLinkState.py
+++ b/src/trezor/messages/DebugLinkState.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .HDNodeType import HDNodeType
 
diff --git a/src/trezor/messages/DebugLinkStop.py b/src/trezor/messages/DebugLinkStop.py
index 92e37c82d8..e113cdf583 100644
--- a/src/trezor/messages/DebugLinkStop.py
+++ b/src/trezor/messages/DebugLinkStop.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DebugLinkStop(p.MessageType):
diff --git a/src/trezor/messages/DecryptMessage.py b/src/trezor/messages/DecryptMessage.py
index 5ef7baf1c5..09e7c53ccc 100644
--- a/src/trezor/messages/DecryptMessage.py
+++ b/src/trezor/messages/DecryptMessage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DecryptMessage(p.MessageType):
diff --git a/src/trezor/messages/DecryptedMessage.py b/src/trezor/messages/DecryptedMessage.py
index cdc5823104..4217b3be70 100644
--- a/src/trezor/messages/DecryptedMessage.py
+++ b/src/trezor/messages/DecryptedMessage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class DecryptedMessage(p.MessageType):
diff --git a/src/trezor/messages/ECDHSessionKey.py b/src/trezor/messages/ECDHSessionKey.py
index 61af6e4986..a30cafe1b8 100644
--- a/src/trezor/messages/ECDHSessionKey.py
+++ b/src/trezor/messages/ECDHSessionKey.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ECDHSessionKey(p.MessageType):
diff --git a/src/trezor/messages/EncryptMessage.py b/src/trezor/messages/EncryptMessage.py
index 3d8ea3ced5..0b0a97e9d0 100644
--- a/src/trezor/messages/EncryptMessage.py
+++ b/src/trezor/messages/EncryptMessage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EncryptMessage(p.MessageType):
diff --git a/src/trezor/messages/EncryptedMessage.py b/src/trezor/messages/EncryptedMessage.py
index c26c51df71..79802d13cf 100644
--- a/src/trezor/messages/EncryptedMessage.py
+++ b/src/trezor/messages/EncryptedMessage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EncryptedMessage(p.MessageType):
diff --git a/src/trezor/messages/Entropy.py b/src/trezor/messages/Entropy.py
index b8cc4405c6..1f56df2396 100644
--- a/src/trezor/messages/Entropy.py
+++ b/src/trezor/messages/Entropy.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Entropy(p.MessageType):
diff --git a/src/trezor/messages/EntropyAck.py b/src/trezor/messages/EntropyAck.py
index 1183271f30..ccdb015133 100644
--- a/src/trezor/messages/EntropyAck.py
+++ b/src/trezor/messages/EntropyAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EntropyAck(p.MessageType):
diff --git a/src/trezor/messages/EntropyRequest.py b/src/trezor/messages/EntropyRequest.py
index 3990dd7157..176f603224 100644
--- a/src/trezor/messages/EntropyRequest.py
+++ b/src/trezor/messages/EntropyRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EntropyRequest(p.MessageType):
diff --git a/src/trezor/messages/EstimateTxSize.py b/src/trezor/messages/EstimateTxSize.py
index 6cb000d25e..4272bef9dd 100644
--- a/src/trezor/messages/EstimateTxSize.py
+++ b/src/trezor/messages/EstimateTxSize.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EstimateTxSize(p.MessageType):
diff --git a/src/trezor/messages/EthereumAddress.py b/src/trezor/messages/EthereumAddress.py
index 7e8dc27bc3..c41a1c2b62 100644
--- a/src/trezor/messages/EthereumAddress.py
+++ b/src/trezor/messages/EthereumAddress.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EthereumAddress(p.MessageType):
diff --git a/src/trezor/messages/EthereumGetAddress.py b/src/trezor/messages/EthereumGetAddress.py
index c6c0e669d2..fb454bed3e 100644
--- a/src/trezor/messages/EthereumGetAddress.py
+++ b/src/trezor/messages/EthereumGetAddress.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EthereumGetAddress(p.MessageType):
diff --git a/src/trezor/messages/EthereumSignTx.py b/src/trezor/messages/EthereumSignTx.py
index 17d65ce45d..2703337d38 100644
--- a/src/trezor/messages/EthereumSignTx.py
+++ b/src/trezor/messages/EthereumSignTx.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EthereumSignTx(p.MessageType):
diff --git a/src/trezor/messages/EthereumTxAck.py b/src/trezor/messages/EthereumTxAck.py
index 5c9683d35f..67705ef401 100644
--- a/src/trezor/messages/EthereumTxAck.py
+++ b/src/trezor/messages/EthereumTxAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EthereumTxAck(p.MessageType):
diff --git a/src/trezor/messages/EthereumTxRequest.py b/src/trezor/messages/EthereumTxRequest.py
index 7e07a95dee..37d7008d7f 100644
--- a/src/trezor/messages/EthereumTxRequest.py
+++ b/src/trezor/messages/EthereumTxRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class EthereumTxRequest(p.MessageType):
diff --git a/src/trezor/messages/Failure.py b/src/trezor/messages/Failure.py
index 97e8d2a1fa..19118310db 100644
--- a/src/trezor/messages/Failure.py
+++ b/src/trezor/messages/Failure.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Failure(p.MessageType):
diff --git a/src/trezor/messages/FailureType.py b/src/trezor/messages/FailureType.py
index d0eca25907..6955a9680f 100644
--- a/src/trezor/messages/FailureType.py
+++ b/src/trezor/messages/FailureType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 UnexpectedMessage = const(1)
 ButtonExpected = const(2)
 SyntaxError = const(3)
diff --git a/src/trezor/messages/Features.py b/src/trezor/messages/Features.py
index 865166b05f..e86b471321 100644
--- a/src/trezor/messages/Features.py
+++ b/src/trezor/messages/Features.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .CoinType import CoinType
 
diff --git a/src/trezor/messages/FirmwareErase.py b/src/trezor/messages/FirmwareErase.py
index 903bc7c464..a0c036e8d8 100644
--- a/src/trezor/messages/FirmwareErase.py
+++ b/src/trezor/messages/FirmwareErase.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class FirmwareErase(p.MessageType):
diff --git a/src/trezor/messages/FirmwareRequest.py b/src/trezor/messages/FirmwareRequest.py
index 8a8c9a61fd..bb1f65d390 100644
--- a/src/trezor/messages/FirmwareRequest.py
+++ b/src/trezor/messages/FirmwareRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class FirmwareRequest(p.MessageType):
diff --git a/src/trezor/messages/FirmwareUpload.py b/src/trezor/messages/FirmwareUpload.py
index aaa4f31e30..ae37d13a90 100644
--- a/src/trezor/messages/FirmwareUpload.py
+++ b/src/trezor/messages/FirmwareUpload.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class FirmwareUpload(p.MessageType):
diff --git a/src/trezor/messages/GetAddress.py b/src/trezor/messages/GetAddress.py
index b94f0da592..82fcbd8721 100644
--- a/src/trezor/messages/GetAddress.py
+++ b/src/trezor/messages/GetAddress.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .MultisigRedeemScriptType import MultisigRedeemScriptType
 
diff --git a/src/trezor/messages/GetECDHSessionKey.py b/src/trezor/messages/GetECDHSessionKey.py
index 650b667785..e3c8dab4e1 100644
--- a/src/trezor/messages/GetECDHSessionKey.py
+++ b/src/trezor/messages/GetECDHSessionKey.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .IdentityType import IdentityType
 
diff --git a/src/trezor/messages/GetEntropy.py b/src/trezor/messages/GetEntropy.py
index aa5634f8fa..ff6f9ea1c6 100644
--- a/src/trezor/messages/GetEntropy.py
+++ b/src/trezor/messages/GetEntropy.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class GetEntropy(p.MessageType):
diff --git a/src/trezor/messages/GetFeatures.py b/src/trezor/messages/GetFeatures.py
index d351cc6b17..2648583ef1 100644
--- a/src/trezor/messages/GetFeatures.py
+++ b/src/trezor/messages/GetFeatures.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class GetFeatures(p.MessageType):
diff --git a/src/trezor/messages/GetPublicKey.py b/src/trezor/messages/GetPublicKey.py
index e37fa5c3a6..5904134fd4 100644
--- a/src/trezor/messages/GetPublicKey.py
+++ b/src/trezor/messages/GetPublicKey.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class GetPublicKey(p.MessageType):
diff --git a/src/trezor/messages/HDNodePathType.py b/src/trezor/messages/HDNodePathType.py
index fb835c640d..1068b0c210 100644
--- a/src/trezor/messages/HDNodePathType.py
+++ b/src/trezor/messages/HDNodePathType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .HDNodeType import HDNodeType
 
diff --git a/src/trezor/messages/HDNodeType.py b/src/trezor/messages/HDNodeType.py
index 89fe224ccb..7789098363 100644
--- a/src/trezor/messages/HDNodeType.py
+++ b/src/trezor/messages/HDNodeType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class HDNodeType(p.MessageType):
diff --git a/src/trezor/messages/IdentityType.py b/src/trezor/messages/IdentityType.py
index b628c29aaa..0455a145dc 100644
--- a/src/trezor/messages/IdentityType.py
+++ b/src/trezor/messages/IdentityType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class IdentityType(p.MessageType):
diff --git a/src/trezor/messages/Initialize.py b/src/trezor/messages/Initialize.py
index 808c03c44b..0c4cb1492d 100644
--- a/src/trezor/messages/Initialize.py
+++ b/src/trezor/messages/Initialize.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Initialize(p.MessageType):
diff --git a/src/trezor/messages/InputScriptType.py b/src/trezor/messages/InputScriptType.py
index 9e3907ecea..954b7aae27 100644
--- a/src/trezor/messages/InputScriptType.py
+++ b/src/trezor/messages/InputScriptType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 SPENDADDRESS = const(0)
 SPENDMULTISIG = const(1)
 EXTERNAL = const(2)
diff --git a/src/trezor/messages/LoadDevice.py b/src/trezor/messages/LoadDevice.py
index 63bef4e914..2f272b9bad 100644
--- a/src/trezor/messages/LoadDevice.py
+++ b/src/trezor/messages/LoadDevice.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .HDNodeType import HDNodeType
 
diff --git a/src/trezor/messages/MessageSignature.py b/src/trezor/messages/MessageSignature.py
index 7dcd376e6a..3c6c7f01bd 100644
--- a/src/trezor/messages/MessageSignature.py
+++ b/src/trezor/messages/MessageSignature.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class MessageSignature(p.MessageType):
diff --git a/src/trezor/messages/MessageType.py b/src/trezor/messages/MessageType.py
index 927f5a0ef1..6870942695 100644
--- a/src/trezor/messages/MessageType.py
+++ b/src/trezor/messages/MessageType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 Initialize = const(0)
 Ping = const(1)
 Success = const(2)
diff --git a/src/trezor/messages/MultisigRedeemScriptType.py b/src/trezor/messages/MultisigRedeemScriptType.py
index fe56d291c5..c06f0a6e6b 100644
--- a/src/trezor/messages/MultisigRedeemScriptType.py
+++ b/src/trezor/messages/MultisigRedeemScriptType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .HDNodePathType import HDNodePathType
 
diff --git a/src/trezor/messages/OutputScriptType.py b/src/trezor/messages/OutputScriptType.py
index 4551a68af3..5b0f1d2839 100644
--- a/src/trezor/messages/OutputScriptType.py
+++ b/src/trezor/messages/OutputScriptType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 PAYTOADDRESS = const(0)
 PAYTOSCRIPTHASH = const(1)
 PAYTOMULTISIG = const(2)
diff --git a/src/trezor/messages/PassphraseAck.py b/src/trezor/messages/PassphraseAck.py
index 759a21cca0..db33e825ba 100644
--- a/src/trezor/messages/PassphraseAck.py
+++ b/src/trezor/messages/PassphraseAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class PassphraseAck(p.MessageType):
diff --git a/src/trezor/messages/PassphraseRequest.py b/src/trezor/messages/PassphraseRequest.py
index e973e24710..7d3976b773 100644
--- a/src/trezor/messages/PassphraseRequest.py
+++ b/src/trezor/messages/PassphraseRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class PassphraseRequest(p.MessageType):
diff --git a/src/trezor/messages/PinMatrixAck.py b/src/trezor/messages/PinMatrixAck.py
index 8032777a78..db318827ea 100644
--- a/src/trezor/messages/PinMatrixAck.py
+++ b/src/trezor/messages/PinMatrixAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class PinMatrixAck(p.MessageType):
diff --git a/src/trezor/messages/PinMatrixRequest.py b/src/trezor/messages/PinMatrixRequest.py
index 58f7b8031c..8a7399110f 100644
--- a/src/trezor/messages/PinMatrixRequest.py
+++ b/src/trezor/messages/PinMatrixRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class PinMatrixRequest(p.MessageType):
diff --git a/src/trezor/messages/PinMatrixRequestType.py b/src/trezor/messages/PinMatrixRequestType.py
index 2fba5c9072..9380b49b00 100644
--- a/src/trezor/messages/PinMatrixRequestType.py
+++ b/src/trezor/messages/PinMatrixRequestType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 Current = const(1)
 NewFirst = const(2)
 NewSecond = const(3)
diff --git a/src/trezor/messages/Ping.py b/src/trezor/messages/Ping.py
index 883723217a..6ee6be7e48 100644
--- a/src/trezor/messages/Ping.py
+++ b/src/trezor/messages/Ping.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Ping(p.MessageType):
diff --git a/src/trezor/messages/PublicKey.py b/src/trezor/messages/PublicKey.py
index 4b91d6cf95..98f81d4004 100644
--- a/src/trezor/messages/PublicKey.py
+++ b/src/trezor/messages/PublicKey.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .HDNodeType import HDNodeType
 
diff --git a/src/trezor/messages/RecoveryDevice.py b/src/trezor/messages/RecoveryDevice.py
index f0d07d0525..7706ca762d 100644
--- a/src/trezor/messages/RecoveryDevice.py
+++ b/src/trezor/messages/RecoveryDevice.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class RecoveryDevice(p.MessageType):
diff --git a/src/trezor/messages/RecoveryDeviceType.py b/src/trezor/messages/RecoveryDeviceType.py
index 0223a03ff2..0416a4d014 100644
--- a/src/trezor/messages/RecoveryDeviceType.py
+++ b/src/trezor/messages/RecoveryDeviceType.py
@@ -1,3 +1,5 @@
 # Automatically generated by pb2py
+from micropython import const
+
 ScrambledWords = const(0)
 Matrix = const(1)
diff --git a/src/trezor/messages/RequestType.py b/src/trezor/messages/RequestType.py
index 3140f308fe..4ce14db44d 100644
--- a/src/trezor/messages/RequestType.py
+++ b/src/trezor/messages/RequestType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 TXINPUT = const(0)
 TXOUTPUT = const(1)
 TXMETA = const(2)
diff --git a/src/trezor/messages/ResetDevice.py b/src/trezor/messages/ResetDevice.py
index fca19d50b0..81bce11caa 100644
--- a/src/trezor/messages/ResetDevice.py
+++ b/src/trezor/messages/ResetDevice.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class ResetDevice(p.MessageType):
diff --git a/src/trezor/messages/SetU2FCounter.py b/src/trezor/messages/SetU2FCounter.py
index cb5e0392a8..d72a3ce44d 100644
--- a/src/trezor/messages/SetU2FCounter.py
+++ b/src/trezor/messages/SetU2FCounter.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class SetU2FCounter(p.MessageType):
diff --git a/src/trezor/messages/SignIdentity.py b/src/trezor/messages/SignIdentity.py
index 55b01b95ae..63620c632f 100644
--- a/src/trezor/messages/SignIdentity.py
+++ b/src/trezor/messages/SignIdentity.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .IdentityType import IdentityType
 
diff --git a/src/trezor/messages/SignMessage.py b/src/trezor/messages/SignMessage.py
index 17a1e86a3a..a11774b121 100644
--- a/src/trezor/messages/SignMessage.py
+++ b/src/trezor/messages/SignMessage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class SignMessage(p.MessageType):
diff --git a/src/trezor/messages/SignTx.py b/src/trezor/messages/SignTx.py
index 870865cc09..34cc42ac7b 100644
--- a/src/trezor/messages/SignTx.py
+++ b/src/trezor/messages/SignTx.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class SignTx(p.MessageType):
diff --git a/src/trezor/messages/SignedIdentity.py b/src/trezor/messages/SignedIdentity.py
index 724024273f..f9735b57e7 100644
--- a/src/trezor/messages/SignedIdentity.py
+++ b/src/trezor/messages/SignedIdentity.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class SignedIdentity(p.MessageType):
diff --git a/src/trezor/messages/SimpleSignTx.py b/src/trezor/messages/SimpleSignTx.py
index d56d5f8d7a..93704e5749 100644
--- a/src/trezor/messages/SimpleSignTx.py
+++ b/src/trezor/messages/SimpleSignTx.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .TxInputType import TxInputType
 from .TxOutputType import TxOutputType
diff --git a/src/trezor/messages/Storage.py b/src/trezor/messages/Storage.py
index e934d7531d..dbf1da13df 100644
--- a/src/trezor/messages/Storage.py
+++ b/src/trezor/messages/Storage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .HDNodeType import HDNodeType
 
diff --git a/src/trezor/messages/Success.py b/src/trezor/messages/Success.py
index 5826b55d02..dc9f9c7e0c 100644
--- a/src/trezor/messages/Success.py
+++ b/src/trezor/messages/Success.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class Success(p.MessageType):
diff --git a/src/trezor/messages/TransactionType.py b/src/trezor/messages/TransactionType.py
index f51f80bc02..efbda48df9 100644
--- a/src/trezor/messages/TransactionType.py
+++ b/src/trezor/messages/TransactionType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .TxInputType import TxInputType
 from .TxOutputBinType import TxOutputBinType
diff --git a/src/trezor/messages/TxAck.py b/src/trezor/messages/TxAck.py
index 5e53e76454..fe720e132c 100644
--- a/src/trezor/messages/TxAck.py
+++ b/src/trezor/messages/TxAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .TransactionType import TransactionType
 
diff --git a/src/trezor/messages/TxInputType.py b/src/trezor/messages/TxInputType.py
index 6611608bc5..c44008e27b 100644
--- a/src/trezor/messages/TxInputType.py
+++ b/src/trezor/messages/TxInputType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .MultisigRedeemScriptType import MultisigRedeemScriptType
 
diff --git a/src/trezor/messages/TxOutputBinType.py b/src/trezor/messages/TxOutputBinType.py
index 4e47f71af6..ce6da03985 100644
--- a/src/trezor/messages/TxOutputBinType.py
+++ b/src/trezor/messages/TxOutputBinType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class TxOutputBinType(p.MessageType):
diff --git a/src/trezor/messages/TxOutputType.py b/src/trezor/messages/TxOutputType.py
index 26f657bb80..3021501872 100644
--- a/src/trezor/messages/TxOutputType.py
+++ b/src/trezor/messages/TxOutputType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .MultisigRedeemScriptType import MultisigRedeemScriptType
 
diff --git a/src/trezor/messages/TxRequest.py b/src/trezor/messages/TxRequest.py
index a93fd50016..469e9a1767 100644
--- a/src/trezor/messages/TxRequest.py
+++ b/src/trezor/messages/TxRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 from .TxRequestDetailsType import TxRequestDetailsType
 from .TxRequestSerializedType import TxRequestSerializedType
diff --git a/src/trezor/messages/TxRequestDetailsType.py b/src/trezor/messages/TxRequestDetailsType.py
index 5917ae17b9..ee8f340f2a 100644
--- a/src/trezor/messages/TxRequestDetailsType.py
+++ b/src/trezor/messages/TxRequestDetailsType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class TxRequestDetailsType(p.MessageType):
diff --git a/src/trezor/messages/TxRequestSerializedType.py b/src/trezor/messages/TxRequestSerializedType.py
index 3fb534511a..5cc7445e3d 100644
--- a/src/trezor/messages/TxRequestSerializedType.py
+++ b/src/trezor/messages/TxRequestSerializedType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class TxRequestSerializedType(p.MessageType):
diff --git a/src/trezor/messages/TxSize.py b/src/trezor/messages/TxSize.py
index 5049fbde40..d092ff9ec1 100644
--- a/src/trezor/messages/TxSize.py
+++ b/src/trezor/messages/TxSize.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class TxSize(p.MessageType):
diff --git a/src/trezor/messages/VerifyMessage.py b/src/trezor/messages/VerifyMessage.py
index da3689e127..08e5bcf62c 100644
--- a/src/trezor/messages/VerifyMessage.py
+++ b/src/trezor/messages/VerifyMessage.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class VerifyMessage(p.MessageType):
diff --git a/src/trezor/messages/WipeDevice.py b/src/trezor/messages/WipeDevice.py
index c267caa4d4..71b4229094 100644
--- a/src/trezor/messages/WipeDevice.py
+++ b/src/trezor/messages/WipeDevice.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class WipeDevice(p.MessageType):
diff --git a/src/trezor/messages/WordAck.py b/src/trezor/messages/WordAck.py
index 89271b7480..5f04f32600 100644
--- a/src/trezor/messages/WordAck.py
+++ b/src/trezor/messages/WordAck.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class WordAck(p.MessageType):
diff --git a/src/trezor/messages/WordRequest.py b/src/trezor/messages/WordRequest.py
index 763bc88f0f..5077ff7b45 100644
--- a/src/trezor/messages/WordRequest.py
+++ b/src/trezor/messages/WordRequest.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 import protobuf as p
 
 class WordRequest(p.MessageType):
diff --git a/src/trezor/messages/WordRequestType.py b/src/trezor/messages/WordRequestType.py
index e0baf37631..2c646605a9 100644
--- a/src/trezor/messages/WordRequestType.py
+++ b/src/trezor/messages/WordRequestType.py
@@ -1,4 +1,6 @@
 # Automatically generated by pb2py
+from micropython import const
+
 Plain = const(0)
 Matrix9 = const(1)
 Matrix6 = const(2)
diff --git a/src/trezor/messages/wire_types.py b/src/trezor/messages/wire_types.py
index ad84d3111d..3d9bf0c092 100644
--- a/src/trezor/messages/wire_types.py
+++ b/src/trezor/messages/wire_types.py
@@ -1,3 +1,6 @@
+# Automatically generated by pb2py
+from micropython import const
+
 WordRequest = const(46)
 DebugLinkMemoryWrite = const(112)
 ButtonAck = const(27)
diff --git a/src/trezor/ui/__init__.py b/src/trezor/ui/__init__.py
index 10675faa1b..3d769d75ab 100644
--- a/src/trezor/ui/__init__.py
+++ b/src/trezor/ui/__init__.py
@@ -1,3 +1,5 @@
+from micropython import const
+
 import sys
 import math
 import utime
diff --git a/src/trezor/ui/pin.py b/src/trezor/ui/pin.py
index 7c4f799595..967df753a0 100644
--- a/src/trezor/ui/pin.py
+++ b/src/trezor/ui/pin.py
@@ -2,7 +2,7 @@ from micropython import const
 from trezor import ui, res
 from trezor.crypto import random
 from trezor.ui import display
-from treozr.ui.button import Button, BTN_CLICKED, CLEAR_BUTTON, CLEAR_BUTTON_ACTIVE
+from trezor.ui.button import Button, BTN_CLICKED, CLEAR_BUTTON, CLEAR_BUTTON_ACTIVE
 
 
 def digit_area(i):
diff --git a/tools/build_protobuf b/tools/build_protobuf
index d76dca13bd..627b74fa61 100755
--- a/tools/build_protobuf
+++ b/tools/build_protobuf
@@ -5,6 +5,9 @@ echo > $CURDIR/pb2/__init__.py
 
 INDEX=../src/trezor/messages/wire_types.py
 rm -f $INDEX
+echo '# Automatically generated by pb2py' >> $INDEX
+echo 'from micropython import const' >> $INDEX
+echo '' >> $INDEX
 
 for i in types messages storage ; do
     # Compile .proto files to python2 modules using google protobuf library