diff --git a/src/calibre/devices/winusb.py b/src/calibre/devices/winusb.py
index 10402ab8f5..016867e8db 100644
--- a/src/calibre/devices/winusb.py
+++ b/src/calibre/devices/winusb.py
@@ -5,7 +5,7 @@
 from __future__ import (unicode_literals, division, absolute_import,
                         print_function)
 
-import os, string, _winreg as winreg, re, time, errno
+import os, string, _winreg as winreg, re, time, sys
 from contextlib import contextmanager
 from ctypes import (
     Structure, POINTER, c_ubyte, windll, byref, c_void_p, WINFUNCTYPE,
@@ -13,8 +13,7 @@ from ctypes import (
     wstring_at, addressof, create_unicode_buffer, string_at, c_uint64 as QWORD)
 from ctypes.wintypes import DWORD, WORD, ULONG, LPCWSTR, HWND, BOOL, LPWSTR, UINT, BYTE, HANDLE
 
-from calibre.constants import is64bit
-from calibre.utils.winreg.lib import Key, HKEY_LOCAL_MACHINE
+is64bit = sys.maxsize > (1 << 32)
 
 # Data and function type definitions {{{
 
@@ -426,6 +425,17 @@ def get_device_interface_detail_data(dev_list, p_interface_data, buf=None):
 class NoRemovableDrives(WindowsError):
     pass
 
+def drive_letter_from_volume_devpath(devpath, drive_map):
+    pbuf = create_unicode_buffer(512)
+    if not devpath.endswith(os.sep):
+        devpath += os.sep
+    try:
+        GetVolumeNameForVolumeMountPoint(devpath, pbuf, len(pbuf))
+    except WindowsError:
+        pass
+    else:
+        return drive_map.get(pbuf.value)
+
 def get_removable_drives(debug=False):
     drive_map = get_all_removable_drives()
     if not drive_map:
@@ -460,14 +470,8 @@ def get_removable_drives(debug=False):
                 candidates.append(devid)
             candidates.append(devpath)
 
-            if not devpath.endswith(os.sep):
-                devpath += os.sep
-            try:
-                GetVolumeNameForVolumeMountPoint(devpath, pbuf, len(pbuf))
-            except WindowsError:
-                continue
-            drive_letter = drive_map.get(pbuf.value)
-            if drive_letter is not None:
+            drive_letter = drive_letter_from_volume_devpath(devpath, drive_map)
+            if drive_letter:
                 ans[drive_letter] = candidates
         return ans
 # }}}
@@ -510,45 +514,44 @@ def get_drive_letters_for_device(vendor_id, product_id, debug=False):
                     break
     if found_at is None:
         return ans
-    try:
-        with Key(open_at='SYSTEM\\CurrentControlSet\\Enum\\USB\\VID_%04X&PID_%04X' % (vid, pid), root=HKEY_LOCAL_MACHINE) as key:
-            available_uuids = {uuid.lower() for uuid in key.iterkeynames()}
-    except WindowsError as err:
-        if err.errno != errno.ENOENT:
-            raise
-        return ans
-    if not available_uuids:
+
+    # Get the device ids for all descendants of the found device
+    device_ids = set()
+    for devinst in iterdescendants(devinfo.DevInst):
+        devid, wbuf = get_device_id(devinst, buf=wbuf)
+        device_ids.add(devid.upper().replace(os.sep, '#'))
+    if debug:
+        print('Device ids: %r' % device_ids)
+    if not device_ids:
         return ans
+
+    drive_map = get_all_removable_drives()
+    if not drive_map:
+        raise NoRemovableDrives('No removable drives found!')
+
+    # Now look for volumes whose device path contains one of the child device
+    # ids we found earlier
     with get_device_set() as dev_list:
         interface_data = SP_DEVICE_INTERFACE_DATA()
         interface_data.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA)
         i = -1
-        drive_map = get_all_removable_drives()
-        vbuf = create_unicode_buffer(100)
         while True:
             i += 1
             if not SetupDiEnumDeviceInterfaces(dev_list, None, byref(GUID_DEVINTERFACE_VOLUME), i, byref(interface_data)):
                 break
             buf, devinfo, devpath = get_device_interface_detail_data(dev_list, byref(interface_data), buf)
-            devid, wbuf = get_device_id(devinfo.DevInst, buf=wbuf)
-            if 'USBSTOR' not in devid:
-                continue
-            parts = devid.split('#')
-            if len(parts) < 3:
-                continue
-            uuid = parts[2].partition('&')[0].lower()
-            if uuid not in available_uuids:
-                continue
-            if not devpath.endswith(os.sep):
-                devpath += os.sep
-            try:
-                GetVolumeNameForVolumeMountPoint(devpath, vbuf, len(vbuf))
-            except WindowsError:
-                continue
-            drive_letter = drive_map.get(vbuf.value)
-            if drive_letter is not None:
-                ans.append(drive_letter)
-        return ans
+            devpath = devpath.upper()
+            matched = False
+            for q in device_ids:
+                if q in devpath:
+                    matched = True
+                    break
+            if matched:
+                drive_letter = drive_letter_from_volume_devpath(devpath, drive_map)
+                if drive_letter:
+                    ans.append(drive_letter)
+    return ans
+
 # }}}
 
 def get_usb_devices():  # {{{
@@ -660,6 +663,6 @@ if __name__ == '__main__':
     pprint(get_all_removable_drives())
     rd = get_removable_drives()
     pprint(rd)
-    pprint(get_drive_letters_for_device(0x1949, 0x4))
+    pprint(get_drive_letters_for_device(0x1949, 0x4, debug=True))
     for drive in rd:
         eject_drive(drive)