diff --git a/mopidy/frontends/mpd/translator.py b/mopidy/frontends/mpd/translator.py
index 49fc064d..87708da5 100644
--- a/mopidy/frontends/mpd/translator.py
+++ b/mopidy/frontends/mpd/translator.py
@@ -1,10 +1,11 @@
+import os
 import re
 
 from mopidy import settings
 from mopidy.frontends.mpd import protocol
 from mopidy.utils.path import path_to_uri
 
-def track_to_mpd_format(track, position=None, cpid=None):
+def track_to_mpd_format(track, position=None, cpid=None, key=None):
     """
     Format track for output to MPD client.
 
@@ -32,6 +33,8 @@ def track_to_mpd_format(track, position=None, cpid=None):
     if position is not None and cpid is not None:
         result.append(('Pos', position))
         result.append(('Id', cpid))
+    if key is not None:
+        result.insert(0, ('key', key))
     return result
 
 def track_artists_to_mpd_format(track):
diff --git a/tests/frontends/mpd/serializer_test.py b/tests/frontends/mpd/serializer_test.py
index 09db3394..ba4e8f18 100644
--- a/tests/frontends/mpd/serializer_test.py
+++ b/tests/frontends/mpd/serializer_test.py
@@ -36,6 +36,10 @@ class TrackMpdFormatTest(unittest.TestCase):
         self.assert_(('Pos', 1) in result)
         self.assert_(('Id', 2) in result)
 
+    def test_mpd_format_with_key(self):
+        result = translator.track_to_mpd_format(Track(), key='file.mp3')
+        self.assert_(('key', 'file.mp3') in result)
+
     def test_mpd_format_track_uses_uri_to_mpd_relative_path(self):
         track = Track(uri='file:///dir/subdir/song.mp3')
         path = dict(translator.track_to_mpd_format(track))['file']