diff --git a/src/calibre/gui2/device.py b/src/calibre/gui2/device.py
index f6e24fdb39..53395aa472 100644
--- a/src/calibre/gui2/device.py
+++ b/src/calibre/gui2/device.py
@@ -32,7 +32,7 @@ from calibre.devices.folder_device.driver import FOLDER_DEVICE
 from calibre.devices.bambook.driver import BAMBOOK, BAMBOOKWifi
 from calibre.constants import DEBUG
 from calibre.utils.config import tweaks, device_prefs
-from calibre.utils.magick.draw import thumbnail
+from calibre.utils.img import scale_image
 from calibre.library.save_to_disk import find_plugboard
 from calibre.ptempfile import PersistentTemporaryFile, force_unicode as filename_to_unicode
 # }}}
@@ -926,7 +926,7 @@ class DeviceMixin(object):  # {{{
 
     def set_default_thumbnail(self, height):
         img = I('book.png', data=True)
-        self.default_thumbnail = thumbnail(img, height, height)
+        self.default_thumbnail = scale_image(img, height, height, preserve_aspect_ratio=False)
 
     def connect_to_folder_named(self, folder):
         if os.path.exists(folder) and os.path.isdir(folder):
@@ -1282,7 +1282,7 @@ class DeviceMixin(object):  # {{{
         if self.device_manager.device and \
                 hasattr(self.device_manager.device, 'THUMBNAIL_WIDTH'):
             try:
-                return thumbnail(data,
+                return scale_image(data,
                                  self.device_manager.device.THUMBNAIL_WIDTH,
                                  self.device_manager.device.THUMBNAIL_HEIGHT,
                                  preserve_aspect_ratio=False)
@@ -1292,7 +1292,7 @@ class DeviceMixin(object):  # {{{
         ht = self.device_manager.device.THUMBNAIL_HEIGHT \
                 if self.device_manager else DevicePlugin.THUMBNAIL_HEIGHT
         try:
-            return thumbnail(data, ht, ht,
+            return scale_image(data, ht, ht,
                     compression_quality=self.device_manager.device.THUMBNAIL_COMPRESSION_QUALITY)
         except:
             pass
diff --git a/src/calibre/gui2/store/search/download_thread.py b/src/calibre/gui2/store/search/download_thread.py
index c8e93f290d..3781496bf0 100644
--- a/src/calibre/gui2/store/search/download_thread.py
+++ b/src/calibre/gui2/store/search/download_thread.py
@@ -13,7 +13,7 @@ from Queue import Queue
 
 from calibre import browser
 from calibre.constants import DEBUG
-from calibre.utils.magick.draw import thumbnail
+from calibre.utils.img import scale_image
 
 class GenericDownloadThreadPool(object):
     '''
@@ -161,7 +161,7 @@ class CoverThread(Thread):
                 if result and result.cover_url:
                     with closing(self.br.open(result.cover_url, timeout=timeout)) as f:
                         result.cover_data = f.read()
-                    result.cover_data = thumbnail(result.cover_data, 64, 64)[2]
+                    result.cover_data = scale_image(result.cover_data, 64, 64)[2]
                     callback()
                 self.tasks.task_done()
             except:
diff --git a/src/calibre/utils/img.py b/src/calibre/utils/img.py
index aa8d1c37ca..605305496c 100644
--- a/src/calibre/utils/img.py
+++ b/src/calibre/utils/img.py
@@ -16,10 +16,11 @@ def image_from_data(data):
     return i
 
 def scale_image(data, width=60, height=80, compression_quality=70, as_png=False, preserve_aspect_ratio=True):
+    ''' Scale an image, returning it as either JPEG or PNG data (bytestring).
+    Transparency is alpha blended with white when converting to JPEG. Is thread
+    safe and does not require a QApplication. '''
     # We use Qt instead of ImageMagick here because ImageMagick seems to use
-    # some kind of memory pool, causing memory consumption to sky rocket. Since
-    # we are only using QImage this method is thread safe, and does not require
-    # a QApplication/GUI thread
+    # some kind of memory pool, causing memory consumption to sky rocket.
     if isinstance(data, QImage):
         img = data
     else:
@@ -47,5 +48,3 @@ def scale_image(data, width=60, height=80, compression_quality=70, as_png=False,
     if not img.save(buf, fmt, quality=compression_quality):
         raise ValueError('Failed to export thumbnail image to: ' + fmt)
     return img.width(), img.height(), ba.data()
-
-