diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index 41ca562f1..1091f17f3 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -2183,7 +2183,7 @@ def parse_codecs(codecs_str):
         if codec in ('avc1', 'avc2', 'avc3', 'avc4', 'vp9', 'vp8', 'hev1', 'hev2', 'h263', 'h264', 'mp4v'):
             if not vcodec:
                 vcodec = full_codec
-        elif codec in ('mp4a', 'opus', 'vorbis', 'mp3', 'aac'):
+        elif codec in ('mp4a', 'opus', 'vorbis', 'mp3', 'aac', 'ac-3'):
             if not acodec:
                 acodec = full_codec
         else: