diff --git a/src/calibre/ebooks/metadata/__init__.py b/src/calibre/ebooks/metadata/__init__.py
index 5bbc43b0f3..1a62f8eaaa 100644
--- a/src/calibre/ebooks/metadata/__init__.py
+++ b/src/calibre/ebooks/metadata/__init__.py
@@ -160,8 +160,8 @@ def get_title_sort_pat(lang=None):
     except AttributeError:
         ans = None  # invalid tweak value
     try:
-        ans = frozenset(ans) if ans else frozenset(data['eng'])
-    except:
+        ans = frozenset(ans) if ans is not None else frozenset(data['eng'])
+    except Exception:
         ans = frozenset((r'A\s+', r'The\s+', r'An\s+'))
     ans = '|'.join(ans)
     ans = '^(%s)'%ans
@@ -192,9 +192,10 @@ def title_sort(title, order=None, lang=None):
         except IndexError:
             pass
         else:
-            title = title[len(prep):] + ', ' + prep
-            if title[0] in _ignore_starts:
-                title = title[1:]
+            if prep:
+                title = title[len(prep):] + ', ' + prep
+                if title[0] in _ignore_starts:
+                    title = title[1:]
     return title.strip()