diff --git a/src/calibre/debug.py b/src/calibre/debug.py
index e8bac90dd3..78fc1f2a30 100644
--- a/src/calibre/debug.py
+++ b/src/calibre/debug.py
@@ -31,7 +31,8 @@ Everything after the -- is passed to the script.
 '''))
     parser.add_option('-c', '--command', help=_('Run python code.'))
     parser.add_option('-e', '--exec-file', help=_('Run the python code in file.'))
-    parser.add_option('-f', '--subset-font', help=_('Subset the specified font'))
+    parser.add_option('-f', '--subset-font', action='store_true', default=False,
+                      help=_('Subset the specified font. Use -- after this option to pass option to the font subsetting program.'))
     parser.add_option('-d', '--debug-device-driver', default=False, action='store_true',
                       help=_('Debug device detection'))
     parser.add_option('-g', '--gui',  default=False, action='store_true',
@@ -258,7 +259,7 @@ def main(args=sys.argv):
         shutdown_other()
     elif opts.subset_font:
         from calibre.utils.fonts.sfnt.subset import main
-        main(['subset-font']+[opts.subset_font]+args[1:])
+        main(['subset-font'] + args[1:])
     elif opts.exec_file:
         run_script(opts.exec_file, args[1:])
     elif opts.run_plugin:
diff --git a/src/calibre/utils/fonts/sfnt/subset.py b/src/calibre/utils/fonts/sfnt/subset.py
index ab43571ea4..ffb36b46d9 100644
--- a/src/calibre/utils/fonts/sfnt/subset.py
+++ b/src/calibre/utils/fonts/sfnt/subset.py
@@ -12,6 +12,7 @@ from collections import OrderedDict
 from operator import itemgetter
 from functools import partial
 
+from calibre.utils.icu import safe_chr
 from calibre.utils.fonts.sfnt.container import Sfnt
 from calibre.utils.fonts.sfnt.errors import UnsupportedFont, NoGlyphs
 
@@ -237,6 +238,11 @@ def main(args):
             prints(c, 'is not a single character', file=sys.stderr)
             raise SystemExit(1)
 
+    def conv_code(c):
+        if c.upper()[:2] in ('U+', '0X'):
+            c = int(c[2:], 16)
+        return safe_chr(int(c))
+
     for c in chars:
         if '-' in c:
             parts = [x.strip() for x in c.split('-')]
@@ -244,12 +250,12 @@ def main(args):
                 prints('Invalid range:', c, file=sys.stderr)
                 raise SystemExit(1)
             if opts.codes:
-                parts = tuple(map(unichr, map(int, parts)))
+                parts = tuple(map(conv_code, parts))
             map(not_single, parts)
             ranges.add(tuple(parts))
         else:
             if opts.codes:
-                c = unichr(int(c))
+                c = conv_code(c)
             not_single(c)
             individual.add(c)
     st = time.time()
@@ -325,8 +331,7 @@ def all():
                 print ('Failed!')
                 failed.append((font['full_name'], font['path'], unicode(e)))
             else:
-                averages.append(sum(new_stats.itervalues())/sum(old_stats.itervalues())
-                        * 100)
+                averages.append(sum(new_stats.itervalues())/sum(old_stats.itervalues()) * 100)
                 print ('Reduced to:', '%.1f'%averages[-1] , '%')
     if unsupported:
         print ('\n\nUnsupported:')