diff --git a/qubesmanager/backup.py b/qubesmanager/backup.py
index 9be8354..97a02d9 100644
--- a/qubesmanager/backup.py
+++ b/qubesmanager/backup.py
@@ -25,9 +25,7 @@ from qubesadmin import exc
 from qubesadmin import utils as admin_utils
 from qubes.storage.file import get_disk_usage
 
-from PyQt5 import QtCore  # pylint: disable=import-error
-from PyQt5 import QtWidgets  # pylint: disable=import-error
-from PyQt5 import QtGui
+from PyQt5 import QtCore, QtWidgets, QtGui  # pylint: disable=import-error
 from . import ui_backupdlg  # pylint: disable=no-name-in-module
 from . import multiselectwidget
 
@@ -36,10 +34,7 @@ from . import utils
 
 import grp
 import pwd
-import sys
 import os
-import asyncio
-from contextlib import suppress
 
 
 # pylint: disable=too-few-public-methods
diff --git a/qubesmanager/bootfromdevice.py b/qubesmanager/bootfromdevice.py
index 24f9370..6377a78 100644
--- a/qubesmanager/bootfromdevice.py
+++ b/qubesmanager/bootfromdevice.py
@@ -33,6 +33,7 @@ class VMBootFromDeviceWindow(ui_bootfromdevice.Ui_BootDialog,
 
         self.vm = vm
         self.qapp = qapp
+        self.qubesapp = qubesapp
 
         self.setupUi(self)
         self.setWindowTitle(
diff --git a/qubesmanager/firewall.py b/qubesmanager/firewall.py
index 3120dff..c224d46 100644
--- a/qubesmanager/firewall.py
+++ b/qubesmanager/firewall.py
@@ -326,8 +326,7 @@ class QubesFirewallRulesModel(QtCore.QAbstractItemModel):
                 if rule.action == 'accept':
                     conf['rules'].insert(0, rule)
                     continue
-                else:
-                    raise FirewallModifiedOutsideError('No blacklist support.')
+                raise FirewallModifiedOutsideError('No blacklist support.')
 
             if rule.expire is not None and rule.dsthost is None \
                     and rule.proto is None:
diff --git a/qubesmanager/global_settings.py b/qubesmanager/global_settings.py
index 1b2d027..a2140f7 100644
--- a/qubesmanager/global_settings.py
+++ b/qubesmanager/global_settings.py
@@ -40,7 +40,8 @@ def _run_qrexec_repo(service, arg=''):
     p = subprocess.run(
         ['sudo', cmd, arg],
         stdout=subprocess.PIPE,
-        stderr=subprocess.PIPE
+        stderr=subprocess.PIPE,
+        check=False
     )
     if p.stderr:
         raise RuntimeError('qrexec call stderr was not empty',
diff --git a/qubesmanager/qube_manager.py b/qubesmanager/qube_manager.py
index ccb1098..34d423c 100644
--- a/qubesmanager/qube_manager.py
+++ b/qubesmanager/qube_manager.py
@@ -664,7 +664,7 @@ class VmManagerWindow(ui_qubemanager.Ui_VmManagerWindow, QtWidgets.QMainWindow):
                                                 QtCore.QSize(1100, 600)))
 
     def get_vms_list(self):
-        return [vm for vm in self.qubes_app.domains]
+        return list(self.qubes_app.domains)
 
     def fill_table(self):
         self.table.setSortingEnabled(False)
diff --git a/qubesmanager/restore.py b/qubesmanager/restore.py
index 48f7531..8f873c5 100644
--- a/qubesmanager/restore.py
+++ b/qubesmanager/restore.py
@@ -35,7 +35,7 @@ from . import utils
 
 from multiprocessing import Queue
 from queue import Empty
-from qubesadmin import Qubes, exc
+from qubesadmin import exc
 from qubesadmin.backup import restore
 
 
diff --git a/qubesmanager/utils.py b/qubesmanager/utils.py
index 5b12256..0a19226 100644
--- a/qubesmanager/utils.py
+++ b/qubesmanager/utils.py
@@ -30,7 +30,7 @@ import sys
 import quamash
 from qubesadmin import events
 
-from PyQt5 import QtWidgets
+from PyQt5 import QtWidgets  # pylint: disable=import-error
 from PyQt5.QtGui import QIcon  # pylint: disable=import-error
 
 
@@ -235,7 +235,7 @@ def loop_shutdown():
 # Copyright (c) 2002-2007 Pascal Varet <p.varet@gmail.com>
 def handle_exception(exc_type, exc_value, exc_traceback):
 
-    filename, line, dummy, dummy = traceback.extract_tb(exc_traceback).pop()
+    filename, line, _, _ = traceback.extract_tb(exc_traceback).pop()
     filename = os.path.basename(filename)
     error = "%s: %s" % (exc_type.__name__, exc_value)