diff --git a/src/N_m3u8DL-RE/DownloadManager/SimpleDownloadManager.cs b/src/N_m3u8DL-RE/DownloadManager/SimpleDownloadManager.cs
index 80d6226..0306248 100644
--- a/src/N_m3u8DL-RE/DownloadManager/SimpleDownloadManager.cs
+++ b/src/N_m3u8DL-RE/DownloadManager/SimpleDownloadManager.cs
@@ -356,7 +356,8 @@ namespace N_m3u8DL_RE.DownloadManager
                 {
                     var files = FileDic.Values.Select(v => v!.ActualFilePath).OrderBy(s => s).ToArray();
                     Logger.InfoMarkUp(ResString.ffmpegMerge);
-                    mergeSuccess = MergeUtil.MergeByFFmpeg(DownloaderConfig.FFmpegBinaryPath!, files, Path.ChangeExtension(output, null), "mp4");
+                    var ext = streamSpec.MediaType == MediaType.AUDIO ? "m4a" : "mp4";
+                    mergeSuccess = MergeUtil.MergeByFFmpeg(DownloaderConfig.FFmpegBinaryPath!, files, Path.ChangeExtension(output, null), ext);
                 }
             }
 
diff --git a/src/N_m3u8DL-RE/Util/MergeUtil.cs b/src/N_m3u8DL-RE/Util/MergeUtil.cs
index 51b9504..558520b 100644
--- a/src/N_m3u8DL-RE/Util/MergeUtil.cs
+++ b/src/N_m3u8DL-RE/Util/MergeUtil.cs
@@ -85,6 +85,9 @@ namespace N_m3u8DL_RE.Util
                 case ("FLV"):
                     command.Append("\" -map 0  -c copy -y " + (useAACFilter ? "-bsf:a aac_adtstoasc" : "") + " \"" + outputPath + ".flv\"");
                     break;
+                case ("M4A"):
+                    command.Append("\" -map 0  -c copy -y " + (useAACFilter ? "-bsf:a aac_adtstoasc" : "") + " \"" + outputPath + ".m4a\"");
+                    break;
                 case ("TS"):
                     command.Append("\" -map 0  -c copy -y -f mpegts -bsf:v h264_mp4toannexb \"" + outputPath + ".ts\"");
                     break;