diff --git a/src/calibre/gui2/tag_browser/model.py b/src/calibre/gui2/tag_browser/model.py
index 2950b9dc4c..d6d62af83c 100644
--- a/src/calibre/gui2/tag_browser/model.py
+++ b/src/calibre/gui2/tag_browser/model.py
@@ -409,7 +409,8 @@ class TagsModel(QAbstractItemModel): # {{{
                 # in ICU's 'ordinal' for the first letter. In this case, the
                 # first letter can actually be more than one letter long.
                 cl_list = [None] * len(data[key])
-                last_ordnum = last_c = 0
+                last_ordnum = 0
+                last_c = ' '
                 for idx,tag in enumerate(data[key]):
                     if not tag.sort:
                         c = ' '