diff --git a/src/calibre/devices/kindle/driver.py b/src/calibre/devices/kindle/driver.py
index a12ad5ebce..1971faef60 100644
--- a/src/calibre/devices/kindle/driver.py
+++ b/src/calibre/devices/kindle/driver.py
@@ -13,7 +13,6 @@ import datetime, os, re, sys, json, hashlib
 from calibre.devices.kindle.bookmark import Bookmark
 from calibre.devices.usbms.driver import USBMS
 from calibre import strftime
-from calibre.utils.logging import default_log
 
 '''
 Notes on collections:
@@ -389,6 +388,7 @@ class KINDLE2(KINDLE):
         self.upload_apnx(path, filename, metadata, filepath)
 
     def upload_kindle_thumbnail(self, metadata, filepath):
+        from calibre.utils.logging import default_log
         coverdata = getattr(metadata, 'thumbnail', None)
         if not coverdata or not coverdata[2]:
             return
diff --git a/src/calibre/devices/smart_device_app/driver.py b/src/calibre/devices/smart_device_app/driver.py
index bae5d82ba3..b7857b14d4 100644
--- a/src/calibre/devices/smart_device_app/driver.py
+++ b/src/calibre/devices/smart_device_app/driver.py
@@ -36,13 +36,9 @@ def synchronous(tlockname):
 
     def _synched(func):
         @wraps(func)
-        def _synchronizer(self,*args, **kwargs):
-            tlock = self.__getattribute__( tlockname)
-            tlock.acquire()
-            try:
+        def _synchronizer(self, *args, **kwargs):
+            with self.__getattribute__(tlockname):
                 return func(self, *args, **kwargs)
-            finally:
-                tlock.release()
         return _synchronizer
     return _synched
 
@@ -466,12 +462,12 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
             ans = select.select((self.listen_socket,), (), (), 0)
             if len(ans[0]) > 0:
                 # timeout in 10 ms to detect rare case where the socket went
-                # way between the select and the accent
+                # way between the select and the accept
                 try:
                     self.device_socket = None
                     self.listen_socket.settimeout(0.010)
-                    self.device_socket, ign = \
-                                eintr_retry_call(self.listen_socket.accept)
+                    self.device_socket, ign = eintr_retry_call(
+                            self.listen_socket.accept)
                     self.listen_socket.settimeout(None)
                     self.device_socket.settimeout(None)
                     self.is_connected = True