diff --git a/src/calibre/devices/smart_device_app/driver.py b/src/calibre/devices/smart_device_app/driver.py
index 862a170866..481a09dd8b 100644
--- a/src/calibre/devices/smart_device_app/driver.py
+++ b/src/calibre/devices/smart_device_app/driver.py
@@ -14,13 +14,12 @@ import random
 import select
 import socket
 import sys
-import threading
 import time
 import traceback
 from collections import defaultdict
 from errno import EAGAIN, EINTR
 from functools import wraps
-from threading import Thread
+from threading import RLock, Thread
 
 from calibre import prints
 from calibre.constants import DEBUG, cache_dir, numeric_version
@@ -62,8 +61,7 @@ def synchronous(tlockname):
 class ConnectionListener(Thread):
 
     def __init__(self, driver):
-        Thread.__init__(self)
-        self.daemon = True
+        super().__init__(name='SmartDeviceConnectionListener', daemon=True)
         self.driver = driver
         self.keep_running = True
         self.all_ip_addresses = {}
@@ -384,7 +382,7 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
     }
 
     def __init__(self, path):
-        self.sync_lock = threading.RLock()
+        self.sync_lock = RLock()
         self.noop_counter = 0
         self.noop_time = time.monotonic()
         self.debug_start_time = time.time()
diff --git a/src/calibre/gui2/ui.py b/src/calibre/gui2/ui.py
index 352f5cf956..7565d7562d 100644
--- a/src/calibre/gui2/ui.py
+++ b/src/calibre/gui2/ui.py
@@ -1242,6 +1242,8 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
         st = monotonic()
         timed_print('Shutdown starting...')
         self.shutting_down = True
+        if (dm := self.device_manager).is_running('smartdevice'):
+            dm.stop_plugin('smartdevice')
         if hasattr(self.library_view, 'connect_to_book_display_timer'):
             self.library_view.connect_to_book_display_timer.stop()
         self.shutdown_started.emit()