diff --git a/src/calibre/ebooks/metadata/meta.py b/src/calibre/ebooks/metadata/meta.py
index a239933710..e74ce5757d 100644
--- a/src/calibre/ebooks/metadata/meta.py
+++ b/src/calibre/ebooks/metadata/meta.py
@@ -31,7 +31,7 @@ def metadata_from_formats(formats):
     try:
         return _metadata_from_formats(formats)
     except:
-        mi = metadata_from_filename(formats[0])
+        mi = metadata_from_filename(list(formats)[0])
         if not mi.authors:
             mi.authors = [_('Unknown')]
 
@@ -126,14 +126,10 @@ def metadata_from_filename(name, pat=None):
             mi.title = match.group('title')
         except IndexError:
             pass
-        try:
-            mi.authors = [match.group('author')]
-        except IndexError:
-            pass
         try:
             au = match.group('authors')
             aus = string_to_authors(au)
-            mi.authors = authors
+            mi.authors = aus
         except IndexError:
             pass
         try:
diff --git a/src/calibre/ebooks/mobi/writer.py b/src/calibre/ebooks/mobi/writer.py
index a5b13e1437..8e8cff2aff 100644
--- a/src/calibre/ebooks/mobi/writer.py
+++ b/src/calibre/ebooks/mobi/writer.py
@@ -2031,7 +2031,7 @@ class MobiWriter(object):
         indices.write(pack('>H', pos))								# Save the offset for IDXTIndices
         name = "%04X"%count
         indxt.write(chr(len(name)) + name)							# Write the name
-        indxt.write(INDXT['section'])   						    # entryType [0x0F | 0xDF | 0xFF | 0x3F]
+        indxt.write(INDXT['section'])                               # entryType [0x0F | 0xDF | 0xFF | 0x3F]
         indxt.write(chr(0))                                         # subType 0
         indxt.write(decint(offset, DECINT_FORWARD))					# offset
         indxt.write(decint(length, DECINT_FORWARD))					# length
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 3550253ffa..fccd131761 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -1708,7 +1708,7 @@ books_series_link      feeds
         formats = self.find_books_in_directory(dirpath, True)
         if not formats:
             return
-
+        formats = list(formats)
         mi = metadata_from_formats(formats)
         if mi.title is None:
             return