diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index 9691a1ea7c..a571f4ede3 100644
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -3546,7 +3546,8 @@ def ffmpeg_fixup(cndn, msg, cls):
                                      'writing DASH m4a. Only some players support this container',
                                      FFmpegFixupM4aPP)
                         ffmpeg_fixup(downloader == 'hlsnative' and not self.params.get('hls_use_mpegts')
-                                     or info_dict.get('is_live') and self.params.get('hls_use_mpegts') is None,
+                                     or info_dict.get('is_live') and self.params.get('hls_use_mpegts') is None
+                                     or downloader == 'niconico_live',
                                      'Possible MPEG-TS in MP4 container or malformed AAC timestamps',
                                      FFmpegFixupM3u8PP)
                         ffmpeg_fixup(downloader == 'dashsegments'
diff --git a/yt_dlp/downloader/__init__.py b/yt_dlp/downloader/__init__.py
index 9f6385058c..51a9f28f06 100644
--- a/yt_dlp/downloader/__init__.py
+++ b/yt_dlp/downloader/__init__.py
@@ -50,7 +50,7 @@ def get_suitable_downloader(info_dict, params={}, default=NO_DEFAULT, protocol=N
     'ism': IsmFD,
     'mhtml': MhtmlFD,
     'niconico_dmc': NiconicoDmcFD,
-    'm3u8_niconico_live': NiconicoLiveFD,
+    'niconico_live': NiconicoLiveFD,
     'fc2_live': FC2LiveFD,
     'websocket_frag': WebSocketFragmentFD,
     'youtube_live_chat': YoutubeLiveChatFD,
diff --git a/yt_dlp/extractor/niconico.py b/yt_dlp/extractor/niconico.py
index 9649329327..11d23f5af1 100644
--- a/yt_dlp/extractor/niconico.py
+++ b/yt_dlp/extractor/niconico.py
@@ -1007,7 +1007,7 @@ def _yield_formats(self, ws_url, headers, latency, video_id, is_live):
         for fmt, q in zip(formats, reversed(qualities[1:])):
             fmt.update({
                 'format_id': q,
-                'protocol': 'm3u8_niconico_live',
+                'protocol': 'niconico_live',
             })
             yield fmt
 
diff --git a/yt_dlp/postprocessor/ffmpeg.py b/yt_dlp/postprocessor/ffmpeg.py
index 164c46d143..422aab8242 100644
--- a/yt_dlp/postprocessor/ffmpeg.py
+++ b/yt_dlp/postprocessor/ffmpeg.py
@@ -888,7 +888,7 @@ def run(self, info):
 class FFmpegFixupM3u8PP(FFmpegFixupPostProcessor):
     def _needs_fixup(self, info):
         yield info['ext'] in ('mp4', 'm4a')
-        yield info['protocol'].startswith('m3u8')
+        yield info['protocol'].startswith('m3u8') or info['protocol'] == 'niconico_live'
         try:
             metadata = self.get_metadata_object(info['filepath'])
         except PostProcessingError as e: