diff --git a/src/calibre/ebooks/metadata/__init__.py b/src/calibre/ebooks/metadata/__init__.py
index 8a08817450..1b80da5d09 100644
--- a/src/calibre/ebooks/metadata/__init__.py
+++ b/src/calibre/ebooks/metadata/__init__.py
@@ -395,7 +395,7 @@ def check_doi(doi):
     return None
 
 def rating_to_stars(value, allow_half_stars=False, star=u'★', half=u'½'):
-    r = max(0, min(int(value), 10))
+    r = max(0, min(int(value or 0), 10))
     if allow_half_stars:
         ans = u'★' * (r // 2)
         if r % 2:
diff --git a/src/calibre/ebooks/metadata/book/render.py b/src/calibre/ebooks/metadata/book/render.py
index b0f07ec24c..b930b080a2 100644
--- a/src/calibre/ebooks/metadata/book/render.py
+++ b/src/calibre/ebooks/metadata/book/render.py
@@ -11,7 +11,7 @@ from functools import partial
 from binascii import hexlify
 
 from calibre import prepare_string_for_xml, force_unicode
-from calibre.ebooks.metadata import fmt_sidx
+from calibre.ebooks.metadata import fmt_sidx, rating_to_stars
 from calibre.ebooks.metadata.sources.identify import urls_from_identifiers
 from calibre.constants import filesystem_encoding
 from calibre.library.comments import comments_to_html, markdown
@@ -106,12 +106,7 @@ def mi_to_html(mi, field_list=None, default_author_link=None, use_roman_numbers=
         elif metadata['datatype'] == 'rating':
             val = getattr(mi, field)
             if val:
-                if disp.get('allow_half_stars'):
-                    val = max(0, min(int(val), 10))
-                    star_string = u'\u2605' * (val // 2) + (u'\u00bd' if val % 2 else '')
-                else:
-                    val = max(0, min(int(val/2.0), 5))
-                    star_string = u'\u2605' * val
+                star_string = rating_to_stars(val, disp.get('allow_half_stars', False))
                 ans.append((field,
                     u'<td class="title">%s</td><td class="rating value" '
                     'style=\'font-family:"%s"\'>%s</td>'%(
diff --git a/src/calibre/gui2/cover_flow.py b/src/calibre/gui2/cover_flow.py
index 5c19934e87..1a22c2c685 100644
--- a/src/calibre/gui2/cover_flow.py
+++ b/src/calibre/gui2/cover_flow.py
@@ -13,6 +13,7 @@ from PyQt5.Qt import (QImage, QSizePolicy, QTimer, QDialog, Qt, QSize, QAction,
         QStackedLayout, QLabel, QByteArray, pyqtSignal, QKeySequence, QFont)
 
 from calibre import plugins
+from calibre.ebooks.metadata import rating_to_stars
 from calibre.constants import islinux
 from calibre.gui2 import (config, available_height, available_width, gprefs,
         rating_font)
@@ -125,7 +126,7 @@ if pictureflow is not None:
         def subtitle(self, index):
             if gprefs['show_rating_in_cover_browser']:
                 try:
-                    return u'\u2605'*self.model.rating(index)
+                    return rating_to_stars(self.model.rating(index) * 2)
                 except:
                     pass
             return ''
diff --git a/src/calibre/gui2/library/alternate_views.py b/src/calibre/gui2/library/alternate_views.py
index ace9ad5de3..b8083e3a54 100644
--- a/src/calibre/gui2/library/alternate_views.py
+++ b/src/calibre/gui2/library/alternate_views.py
@@ -23,7 +23,7 @@ from PyQt5.Qt import (
 
 from calibre import fit_image, prints, prepare_string_for_xml, human_readable
 from calibre.constants import DEBUG, config_dir
-from calibre.ebooks.metadata import fmt_sidx
+from calibre.ebooks.metadata import fmt_sidx, rating_to_stars
 from calibre.utils import join_with_timeout
 from calibre.gui2 import gprefs, config
 from calibre.gui2.library.caches import CoverCache, ThumbnailCache
@@ -392,7 +392,7 @@ class CoverDelegate(QStyledItemDelegate):
                 mi = db.get_proxy_metadata(book_id)
                 display_name, ans, val, fm = mi.format_field_extended(field)
                 if fm and fm['datatype'] == 'rating':
-                    ans = u'\u2605' * int(val/2.0) if val is not None else ''
+                    ans = rating_to_stars(val, fm['display'].get('allow_half_stars', False))
             return '' if ans is None else unicode(ans)
         except Exception:
             if DEBUG:
diff --git a/src/calibre/utils/fonts/utils.py b/src/calibre/utils/fonts/utils.py
index 11154057fd..f3b2709e95 100644
--- a/src/calibre/utils/fonts/utils.py
+++ b/src/calibre/utils/fonts/utils.py
@@ -418,7 +418,7 @@ def test_glyph_ids():
 
 def test_supports_text():
     data = P('fonts/calibreSymbols.otf', data=True)
-    if not supports_text(data, '.\u2605★'):
+    if not supports_text(data, '.★½'):
         raise RuntimeError('Incorrectly returning that text is not supported')
     if supports_text(data, 'abc'):
         raise RuntimeError('Incorrectly claiming that text is supported')