diff --git a/src/calibre/ebooks/metadata/meta.py b/src/calibre/ebooks/metadata/meta.py
index 8da74ceb8f..76d04045c2 100644
--- a/src/calibre/ebooks/metadata/meta.py
+++ b/src/calibre/ebooks/metadata/meta.py
@@ -136,7 +136,7 @@ def metadata_from_filename(name, pat=None):
         try:
             si = match.group('series_index')
             mi.series_index = int(si)
-        except (IndexError, ValueError):
+        except (IndexError, ValueError, TypeError):
             pass
         try:
             si = match.group('isbn')
diff --git a/src/calibre/gui2/filename_pattern.ui b/src/calibre/gui2/filename_pattern.ui
index 30fc1b6ac0..cd43c297d3 100644
--- a/src/calibre/gui2/filename_pattern.ui
+++ b/src/calibre/gui2/filename_pattern.ui
@@ -169,7 +169,7 @@
         <item row="5" column="1" >
          <widget class="QLineEdit" name="isbn" >
           <property name="toolTip" >
-           <string>Regular expression group name (?P&lt;series_index>)</string>
+           <string>Regular expression group name (?P&lt;isbn>)</string>
           </property>
           <property name="text" >
            <string>No match</string>