diff --git a/feeluown/player/playlist.py b/feeluown/player/playlist.py
index ad5b175de..d5af50251 100644
--- a/feeluown/player/playlist.py
+++ b/feeluown/player/playlist.py
@@ -118,7 +118,10 @@ def __init__(self, app: 'App', songs=None, playback_mode=PlaybackMode.loop,
         #: store value for ``songs`` property
         self._songs = DedupList(songs or [])
         # Acquire this lock before changing _current_song or _songs.
-        # TODO: use emit_nowait???
+        # NOTE: some methods emit some signal while holding the lock,
+        #   the signal handler should pay much attention to avoid deadlock.
+        #   One thing is that the signal handler should not call any method
+        #   that requires the lock!!!
         self._songs_lock = Lock()
 
         self.audio_select_policy = audio_select_policy
@@ -166,13 +169,13 @@ def mode(self):
     def mode(self, mode):
         """set playlist mode"""
         if self._mode is not mode:
+            # we should change _mode at the very end
+            self._mode = mode
             if mode is PlaylistMode.fm:
                 self._normal_mode_playback_mode = self.playback_mode
                 self.playback_mode = PlaybackMode.sequential
             else:
                 self.playback_mode = self._normal_mode_playback_mode
-            # we should change _mode at the very end
-            self._mode = mode
             self.mode_changed.emit(mode)
             logger.info('playlist mode changed to %s', mode)
 
diff --git a/tests/player/test_playlist.py b/tests/player/test_playlist.py
index 2db7c8cbf..4c8a05c43 100644
--- a/tests/player/test_playlist.py
+++ b/tests/player/test_playlist.py
@@ -187,8 +187,8 @@ def mock_prepare_metadata(mocker):
 async def test_playlist_change_mode(app_mock, mocker):
     # from normal to fm
     pl = Playlist(app_mock)
-    pl.mode = PlaylistMode.fm
     old_playback_mode = pl.playback_mode
+    pl.mode = PlaylistMode.fm
     assert pl.playback_mode is PlaybackMode.sequential
 
     # from fm to normal