diff --git a/server/models/song.js b/server/models/song.js
index c4f372a..41d0779 100644
--- a/server/models/song.js
+++ b/server/models/song.js
@@ -11,6 +11,8 @@ const SongSchema = new Schema({
     type: Schema.Types.ObjectId,
     ref: 'lyric'
   }]
+}, {
+  usePushEach: true,
 });
 
 SongSchema.statics.addLyric = function(id, content) {
@@ -19,7 +21,7 @@ SongSchema.statics.addLyric = function(id, content) {
   return this.findById(id)
     .then(song => {
       const lyric = new Lyric({ content, song })
-      song.lyrics.push(lyric)
+      song.lyrics.push(lyric.id)
       return Promise.all([lyric.save(), song.save()])
         .then(([lyric, song]) => song);
     });