diff --git a/mmgen/main_addrimport.py b/mmgen/main_addrimport.py
index 83321a1b..320d7178 100755
--- a/mmgen/main_addrimport.py
+++ b/mmgen/main_addrimport.py
@@ -81,7 +81,7 @@ addrimport_msgs = {
 	"""
 }
 
-def parse_cmd_args(rpc, cmd_args):
+def parse_cmd_args(cmd_args):
 
 	def import_mmgen_list(infile):
 		return (AddrList, KeyAddrList)[bool(cfg.keyaddr_file)](cfg, proto, infile=infile)
@@ -146,7 +146,7 @@ async def main():
 	for k, v in addrimport_msgs.items():
 		addrimport_msgs[k] = fmt(v, indent='  ', strip_char='\t').rstrip()
 
-	al, infile = parse_cmd_args(twctl.rpc, cfg._args)
+	al, infile = parse_cmd_args(cfg._args)
 
 	cfg._util.qmsg(
 		f'OK. {al.num_addrs} addresses'
diff --git a/mmgen/obj.py b/mmgen/obj.py
index 4941b05d..e12d70fd 100755
--- a/mmgen/obj.py
+++ b/mmgen/obj.py
@@ -124,10 +124,11 @@ class ImmutableAttr: # Descriptor
 			def assign_with_check(instance, value):
 				if type(value) is dtype:
 					return value
-				raise TypeError('Attribute {!r} of {} instance must of type {}'.format(
+				raise TypeError('Attribute {!r} of {} instance must be of type {}, not {}'.format(
 					self.name,
 					type(instance).__name__,
-					dtype))
+					dtype,
+					type(value)))
 			self.conv = assign_with_check
 
 	def __set_name__(self, owner, name):
diff --git a/mmgen/proto/btc/tw/ctl.py b/mmgen/proto/btc/tw/ctl.py
index 1af357dd..4c34f2bf 100755
--- a/mmgen/proto/btc/tw/ctl.py
+++ b/mmgen/proto/btc/tw/ctl.py
@@ -20,9 +20,6 @@ class BitcoinTwCtl(TwCtl):
 	def init_empty(self):
 		self.data = {'coin': self.proto.coin, 'addresses': {}}
 
-	def upgrade_wallet_maybe(self):
-		pass
-
 	async def rpc_get_balance(self, addr, block='latest'):
 		raise NotImplementedError('not implemented')
 
diff --git a/mmgen/proto/eth/tw/ctl.py b/mmgen/proto/eth/tw/ctl.py
index 59493363..30098e9e 100755
--- a/mmgen/proto/eth/tw/ctl.py
+++ b/mmgen/proto/eth/tw/ctl.py
@@ -174,7 +174,7 @@ class EthereumTwCtl(TwCtl):
 	def used_addrs(self):
 		from decimal import Decimal
 		return (
-			{k for k, v in self.data['accounts'].items() if Decimal(v['balance'])} |
+			{k for k, v in self.data['accounts'].items() if Decimal(v.get('balance', 0))} |
 			{k for t in self.data['tokens'].values() for k, v in t.items()
 				if Decimal(v.get('balance', 0))})
 
diff --git a/mmgen/tw/addresses.py b/mmgen/tw/addresses.py
index d3ad0fe4..ddcbc24c 100755
--- a/mmgen/tw/addresses.py
+++ b/mmgen/tw/addresses.py
@@ -132,7 +132,7 @@ class TwAddresses(TwView):
 				(not (d.is_used and not self.showused) and (d.amt or self.showempty))
 			)
 
-	def get_column_widths(self, data, wide, interactive):
+	def get_column_widths(self, data, *, wide, interactive):
 
 		return self.compute_column_widths(
 			widths = { # fixed cols
diff --git a/mmgen/tw/ctl.py b/mmgen/tw/ctl.py
index 5ea59330..d9330785 100755
--- a/mmgen/tw/ctl.py
+++ b/mmgen/tw/ctl.py
@@ -110,6 +110,9 @@ class TwCtl(MMGenObject, metaclass=AsyncInit):
 
 		self.conv_types(self.data[self.data_key])
 
+	def upgrade_wallet_maybe(self):
+		pass
+
 	def init_from_wallet_file(self):
 		from ..fileutil import check_or_create_dir, get_data_from_file
 		check_or_create_dir(self.tw_dir)
diff --git a/test/cmdtest_d/ethswap.py b/test/cmdtest_d/ethswap.py
index 6401d3f6..cd5b73d4 100755
--- a/test/cmdtest_d/ethswap.py
+++ b/test/cmdtest_d/ethswap.py
@@ -466,7 +466,8 @@ class CmdTestEthSwapEth(CmdTestEthSwapMethods, CmdTestSwapMethods, CmdTestEthdev
 		return self._swaptxsend(add_opts=['--verbose', '--status'], status=True)
 
 	def swaptxmemo4(self):
-		self.mining_delay()
+		import time
+		time.sleep(1)
 		return self._check_token_swaptx_memo('=:b:mkQsXA7mqDtnUpkaXMbDtAL1KMeof4GPw3:0/3/0')
 
 	def swaptxreceipt4(self):