diff --git a/src/calibre/ebooks/docx/numbering.py b/src/calibre/ebooks/docx/numbering.py
index 602689a8cd..740674d0dd 100644
--- a/src/calibre/ebooks/docx/numbering.py
+++ b/src/calibre/ebooks/docx/numbering.py
@@ -90,7 +90,7 @@ class Level(object):
                 self.is_numbered = False
                 cs = self.character_style
                 if lt in {'\uf0a7', 'o'} or (
-                    cs.font_family is not inherit and cs.font_family.lower() in {'wingdings', 'symbol'}):
+                    cs is not None and cs.font_family is not inherit and cs.font_family.lower() in {'wingdings', 'symbol'}):
                     self.fmt = {'\uf0a7':'square', 'o':'circle'}.get(lt, 'disc')
                 else:
                     self.bullet_template = lt