diff --git a/yt_dlp/postprocessor/embedthumbnail.py b/yt_dlp/postprocessor/embedthumbnail.py
index fb778e233..5fd92fd34 100644
--- a/yt_dlp/postprocessor/embedthumbnail.py
+++ b/yt_dlp/postprocessor/embedthumbnail.py
@@ -100,7 +100,7 @@ def run(self, info):
                         del audio['APIC']
                     with open(thumbnail_filename, 'rb') as thumbfile:
                         audio['APIC'] = mutagen.id3.APIC(
-                            encoding=3, mime='image/%s' % thumbnail_ext, type=3,
+                            encoding=mutagen.id3.Encoding.UTF8, mime='image/%s' % thumbnail_ext, type=3,
                             desc=u'Cover (front)', data=thumbfile.read())
                     audio.save()
                     temp_filename = filename  # Mutagen saves to the original file
diff --git a/yt_dlp/postprocessor/ffmpeg.py b/yt_dlp/postprocessor/ffmpeg.py
index 7107574a7..7baff0a67 100644
--- a/yt_dlp/postprocessor/ffmpeg.py
+++ b/yt_dlp/postprocessor/ffmpeg.py
@@ -672,6 +672,8 @@ def run(self, info):
     def embed_lyrics(self, input_files):
         audio_file = input_files[0]
         subs = input_files[1]
+        if len(input_files) > 2:
+            self.report_warning('More than one subtitle file found. Only one will be embedded')
         if not subs.endswith('.lrc'):
             raise PostProcessingError('LRC subtitles required. Use "--convert-subs lrc" to convert')
 
@@ -679,7 +681,7 @@ def embed_lyrics(self, input_files):
             lyrics = f.read().strip()
         if audio_file.endswith('.mp3'):
             audio = mutagen.id3.ID3(audio_file)
-            audio.add(mutagen.id3.USLT(encoding=3, lang='eng', desc='', text=lyrics))
+            audio.add(mutagen.id3.USLT(encoding=mutagen.id3.Encoding.UTF8, lang='und', desc='', text=lyrics))
             audio.save()
         else:
             metadata = mutagen.File(audio_file)