diff --git a/src/calibre/__init__.py b/src/calibre/__init__.py
index c237e15dff..737fa0b383 100644
--- a/src/calibre/__init__.py
+++ b/src/calibre/__init__.py
@@ -445,6 +445,9 @@ def prepare_string_for_xml(raw, attribute=False):
         raw = raw.replace('"', '"').replace("'", ''')
     return raw
 
+def isbytestring(obj):
+    return isinstance(obj, (str, bytes))
+
 if isosx:
     import glob, shutil
     fdir = os.path.expanduser('~/.fonts')
diff --git a/src/calibre/devices/folder_device/driver.py b/src/calibre/devices/folder_device/driver.py
index 00f2db282d..e1c95e865a 100644
--- a/src/calibre/devices/folder_device/driver.py
+++ b/src/calibre/devices/folder_device/driver.py
@@ -54,6 +54,7 @@ class FOLDER_DEVICE(USBMS):
     def __init__(self, path):
         if not os.path.isdir(path):
             raise IOError, 'Path is not a folder'
+        path = USBMS.normalize_path(path)
         if path.endswith(os.sep):
             self._main_prefix = path
         else:
diff --git a/src/calibre/devices/usbms/driver.py b/src/calibre/devices/usbms/driver.py
index 5273ffe579..cd6bddfc28 100644
--- a/src/calibre/devices/usbms/driver.py
+++ b/src/calibre/devices/usbms/driver.py
@@ -15,7 +15,8 @@ import re
 import json
 from itertools import cycle
 
-from calibre import prints
+from calibre import prints, isbytestring
+from calibre.constants import filesystem_encoding
 from calibre.devices.usbms.cli import CLI
 from calibre.devices.usbms.device import Device
 from calibre.devices.usbms.books import BookList, Book
@@ -90,7 +91,6 @@ class USBMS(CLI, Device):
                             #print 'update_metadata_item returned true'
                             changed = True
                     else:
-                        #print "adding new book", lpath
                         if bl.add_book(self.book_from_path(prefix, lpath),
                                               replace_metadata=False):
                             changed = True
@@ -102,6 +102,8 @@ class USBMS(CLI, Device):
         if isinstance(ebook_dirs, basestring):
             ebook_dirs = [ebook_dirs]
         for ebook_dir in ebook_dirs:
+            if isbytestring(ebook_dir):
+                ebook_dir = ebook_dir.decode(filesystem_encoding)
             ebook_dir = self.normalize_path( \
                             os.path.join(prefix, *(ebook_dir.split('/'))) \
                                     if ebook_dir else prefix)
@@ -113,7 +115,8 @@ class USBMS(CLI, Device):
                 for path, dirs, files in os.walk(ebook_dir):
                     for filename in files:
                         if filename != self.METADATA_CACHE:
-                            flist.append({'filename':filename, 'path': path})
+                            flist.append({'filename':filename,
+                                          'path':path})
                 for i, f in enumerate(flist):
                     self.report_progress(i/float(len(flist)), _('Getting list of books on device...'))
                     changed = update_booklist(f['filename'], f['path'], prefix)
@@ -189,20 +192,22 @@ class USBMS(CLI, Device):
         for i, location in enumerate(locations):
             self.report_progress((i+1) / float(len(locations)), _('Adding books to device metadata listing...'))
             info = metadata.next()
-            path = location[0]
             blist = 2 if location[1] == 'cardb' else 1 if location[1] == 'carda' else 0
 
+            # Extract the correct prefix from the pathname. To do this correctly,
+            # we must ensure that both the prefix and the path are normalized
+            # so that the comparison will work. Book's __init__ will fix up
+            # lpath, so we don't need to worry about that here.
+            path = self.normalize_path(location[0])
             if self._main_prefix:
-                # Normalize path and prefix
-                if self._main_prefix.find('\\') >= 0:
-                    path = path.replace('/', '\\')
-                else:
-                    path = path.replace('\\', '/')
-                prefix = self._main_prefix if path.startswith(self._main_prefix) else None
+                prefix = self._main_prefix if \
+                           path.startswith(self.normalize_path(self._main_prefix)) else None
             if not prefix and self._card_a_prefix:
-                prefix = self._card_a_prefix if path.startswith(self._card_a_prefix) else None
+                prefix = self._card_a_prefix if \
+                           path.startswith(self.normalize_path(self._card_a_prefix)) else None
             if not prefix and self._card_b_prefix:
-                prefix = self._card_b_prefix if path.startswith(self._card_b_prefix) else None
+                prefix = self._card_b_prefix if \
+                           path.startswith(self.normalize_path(self._card_b_prefix)) else None
             if prefix is None:
                 prints('in add_books_to_metadata. Prefix is None!', path,
                         self._main_prefix)
@@ -274,6 +279,8 @@ class USBMS(CLI, Device):
             path = path.replace('/', '\\')
         else:
             path = path.replace('\\', '/')
+        if isbytestring(path):
+            path = path.decode(filesystem_encoding)
         return path
 
     @classmethod
diff --git a/src/calibre/utils/windows/winutil.c b/src/calibre/utils/windows/winutil.c
index 2f176043b2..42b6462313 100644
--- a/src/calibre/utils/windows/winutil.c
+++ b/src/calibre/utils/windows/winutil.c
@@ -560,6 +560,7 @@ get_device_ancestors(HDEVINFO hDevInfo, DWORD index, PyObject *candidates, BOOL
         return NULL;
     }
     interfaceDetailData->cbSize = sizeof (SP_INTERFACE_DEVICE_DETAIL_DATA);
+    devInfoData.cbSize = sizeof(SP_DEVINFO_DATA);
 
     status = SetupDiGetDeviceInterfaceDetail (
                   hDevInfo,                 // Interface Device info handle