diff --git a/beets/autotag/mb.py b/beets/autotag/mb.py
index 1cf92ce5d..43639433e 100644
--- a/beets/autotag/mb.py
+++ b/beets/autotag/mb.py
@@ -319,7 +319,7 @@ def match_album(artist, album, tracks=None):
         # Various Artists search.
         criteria['arid'] = VARIOUS_ARTISTS_ID
     if tracks is not None:
-        criteria['tracks'] = bytes(tracks)
+        criteria['tracks'] = unicode(tracks)
 
     # Abort if we have no search terms.
     if not any(criteria.itervalues()):
diff --git a/beets/library.py b/beets/library.py
index cb46d99c3..33aa314bf 100644
--- a/beets/library.py
+++ b/beets/library.py
@@ -393,7 +393,7 @@ class Item(LibModel):
     _search_fields = ('artist', 'title', 'comments',
                       'album', 'albumartist', 'genre')
 
-    _media_fields = set(f.decode('utf8') for f in MediaFile.readable_fields()) \
+    _media_fields = set(MediaFile.readable_fields()) \
         .intersection(_fields.keys())
     """Set of item fields that are backed by `MediaFile` fields.
 
diff --git a/beets/mediafile.py b/beets/mediafile.py
index 9c55f582e..6c5d0a2c2 100644
--- a/beets/mediafile.py
+++ b/beets/mediafile.py
@@ -1431,7 +1431,7 @@ class MediaFile(object):
         """
         for property, descriptor in cls.__dict__.items():
             if isinstance(descriptor, MediaField):
-                yield property
+                yield property.decode('utf8')
 
     @classmethod
     def readable_fields(cls):