diff --git a/mopidy/mpd/protocol/stored_playlists.py b/mopidy/mpd/protocol/stored_playlists.py
index fd395696..affd1126 100644
--- a/mopidy/mpd/protocol/stored_playlists.py
+++ b/mopidy/mpd/protocol/stored_playlists.py
@@ -254,9 +254,12 @@ def playlistdelete(context, name, songpos):
     if not playlist:
         raise exceptions.MpdNoExistError('No such playlist')
 
-    # Convert tracks to list and remove requested
-    tracks = list(playlist.tracks)
-    tracks.pop(songpos)
+    try:
+        # Convert tracks to list and remove requested
+        tracks = list(playlist.tracks)
+        tracks.pop(songpos)
+    except IndexError:
+        raise exceptions.MpdArgError('Bad song index')
 
     # Replace tracks and save playlist
     playlist = playlist.replace(tracks=tracks)
diff --git a/tests/mpd/protocol/test_stored_playlists.py b/tests/mpd/protocol/test_stored_playlists.py
index e33b1bc2..6b568667 100644
--- a/tests/mpd/protocol/test_stored_playlists.py
+++ b/tests/mpd/protocol/test_stored_playlists.py
@@ -314,6 +314,15 @@ class PlaylistsHandlerTest(protocol.BaseTestCase):
                               'invalid: playlist names may not contain '
                               'slashes, newlines or carriage returns')
 
+    def test_playlistdelete_unknown_playlist_acks(self):
+        self.send_request('playlistdelete "foobar" "0"')
+        self.assertInResponse('ACK [50@0] {playlistdelete} No such playlist')
+
+    def test_playlistdelete_unknown_index_acks(self):
+        self.send_request('save "foobar"')
+        self.send_request('playlistdelete "foobar" "0"')
+        self.assertInResponse('ACK [2@0] {playlistdelete} Bad song index')
+
     def test_playlistmove(self):
         tracks = [
             Track(uri='dummy:a'),