diff --git a/src/apps/ethereum/layout.py b/src/apps/ethereum/layout.py
index 25fceda83e..faf4045ff2 100644
--- a/src/apps/ethereum/layout.py
+++ b/src/apps/ethereum/layout.py
@@ -27,7 +27,7 @@ async def require_confirm_fee(ctx, spending, gas_price, gas_limit, chain_id, tok
                    ui.NORMAL, 'Gas price:',
                    ui.BOLD, format_ethereum_amount(gas_price, None, chain_id, tx_type),
                    ui.NORMAL, 'Maximum fee:',
-                   ui.BOLD, format_ethereum_amount(gas_price *gas_limit, None, chain_id, tx_type),
+                   ui.BOLD, format_ethereum_amount(gas_price * gas_limit, None, chain_id, tx_type),
                    icon_color=ui.GREEN)
     await require_hold_to_confirm(ctx, content, ButtonRequestType.SignTx)
 
diff --git a/src/apps/ethereum/networks.py b/src/apps/ethereum/networks.py
index f3a378fe62..9f8a603b4d 100644
--- a/src/apps/ethereum/networks.py
+++ b/src/apps/ethereum/networks.py
@@ -13,7 +13,7 @@ suffixes = {
 
 
 def suffix_by_chain_id(chain_id, tx_type=None):
-    if (tx_type==1 or tx_type==6) and (chain_id==1 or chain_id==3):
-        return"WAN"
+    if tx_type in [1, 6] and chain_id in [1, 3]:
+        return 'WAN'
     else:
         return suffixes.get(chain_id, 'UNKN')
diff --git a/src/apps/ethereum/sign_tx.py b/src/apps/ethereum/sign_tx.py
index 10188748e4..762ddcc870 100644
--- a/src/apps/ethereum/sign_tx.py
+++ b/src/apps/ethereum/sign_tx.py
@@ -46,7 +46,7 @@ async def ethereum_sign_tx(ctx, msg):
     sha = HashWriter(sha3_256)
     sha.extend(rlp.encode_length(total_length, True))  # total length
 
-    if not msg.tx_type is None:
+    if msg.tx_type is not None:
         sha.extend(rlp.encode(msg.tx_type))
 
     for field in [msg.nonce, msg.gas_price, msg.gas_limit, msg.to, msg.value]:
@@ -75,7 +75,7 @@ async def ethereum_sign_tx(ctx, msg):
 
 def get_total_length(msg: EthereumSignTx, data_total: int) -> int:
     length = 0
-    if not msg.tx_type is None:
+    if msg.tx_type is not None:
         length += rlp.field_length(1, [msg.tx_type])
 
     for field in [msg.nonce, msg.gas_price, msg.gas_limit, msg.to, msg.value]:
@@ -130,10 +130,10 @@ def node_derive(root, address_n: list):
 
 def check(msg: EthereumSignTx):
     if msg.tx_type not in [1, 6, None]:
-        raise ValueError(FailureType.DataError, 'Txtype out of bounds')
+        raise wire.DataError('tx_type out of bounds')
 
     if msg.chain_id < 0 or msg.chain_id > MAX_CHAIN_ID:
-        raise wire.DataError('Chain id out of bounds')
+        raise wire.DataError('chain_id out of bounds')
 
     if msg.data_length > 0:
         if not msg.data_initial_chunk:
diff --git a/src/apps/management/recovery_device.py b/src/apps/management/recovery_device.py
index b4c377805c..432edd6650 100644
--- a/src/apps/management/recovery_device.py
+++ b/src/apps/management/recovery_device.py
@@ -2,7 +2,6 @@ from trezor import config, ui, wire
 from trezor.crypto import bip39
 from trezor.messages.ButtonRequest import ButtonRequest
 from trezor.messages.ButtonRequestType import MnemonicWordCount, MnemonicInput
-from trezor.messages.FailureType import ProcessError, UnexpectedMessage
 from trezor.messages.Success import Success
 from trezor.messages.wire_types import ButtonAck
 from trezor.pin import pin_to_int
diff --git a/src/apps/wallet/sign_message.py b/src/apps/wallet/sign_message.py
index 83128ba572..dc6b0b696f 100644
--- a/src/apps/wallet/sign_message.py
+++ b/src/apps/wallet/sign_message.py
@@ -1,7 +1,6 @@
 from trezor import ui, wire
 from trezor.crypto.curve import secp256k1
 from trezor.messages.InputScriptType import SPENDADDRESS, SPENDP2SHWITNESS, SPENDWITNESS
-from trezor.messages.FailureType import ProcessError
 from trezor.messages.MessageSignature import MessageSignature
 from trezor.ui.text import Text
 from apps.common import coins, seed