diff --git a/youtube_dlc/__init__.py b/youtube_dlc/__init__.py
index c17e9a3df..d28510467 100644
--- a/youtube_dlc/__init__.py
+++ b/youtube_dlc/__init__.py
@@ -15,7 +15,6 @@ import sys
 
 from .options import (
     parseOpts,
-    _remux_formats,
 )
 from .compat import (
     compat_getpass,
@@ -32,11 +31,12 @@ from .utils import (
     preferredencoding,
     read_batch_urls,
     RejectedVideoReached,
+    REMUX_EXTENSIONS,
+    render_table,
     SameFileError,
     setproctitle,
     std_headers,
     write_string,
-    render_table,
 )
 from .update import update_self
 from .downloader import (
@@ -210,13 +210,15 @@ def _real_main(argv=None):
         if not opts.audioquality.isdigit():
             parser.error('invalid audio quality specified')
     if opts.recodevideo is not None:
-        if opts.recodevideo not in _remux_formats:
+        if opts.recodevideo not in REMUX_EXTENSIONS:
             parser.error('invalid video recode format specified')
     if opts.remuxvideo and opts.recodevideo:
         opts.remuxvideo = None
         write_string('WARNING: --remux-video is ignored since --recode-video was given\n', out=sys.stderr)
     if opts.remuxvideo is not None:
-        if opts.remuxvideo not in _remux_formats:
+        opts.remuxvideo = opts.remuxvideo.replace(' ', '')
+        remux_regex = r'{0}(?:/{0})*$'.format(r'(?:\w+>)?(?:%s)' % '|'.join(REMUX_EXTENSIONS))
+        if not re.match(remux_regex, opts.remuxvideo):
             parser.error('invalid video remux format specified')
     if opts.convertsubtitles is not None:
         if opts.convertsubtitles not in ['srt', 'vtt', 'ass', 'lrc']:
@@ -352,7 +354,11 @@ def _real_main(argv=None):
         opts.postprocessor_args.setdefault('sponskrub', [])
         opts.postprocessor_args['default'] = opts.postprocessor_args['default-compat']
 
-    audio_ext = opts.audioformat if (opts.extractaudio and opts.audioformat != 'best') else None
+    final_ext = (
+        opts.recodevideo
+        or (opts.remuxvideo in REMUX_EXTENSIONS) and opts.remuxvideo
+        or (opts.extractaudio and opts.audioformat != 'best') and opts.audioformat
+        or None)
 
     match_filter = (
         None if opts.match_filter is None
@@ -473,7 +479,7 @@ def _real_main(argv=None):
         'extract_flat': opts.extract_flat,
         'mark_watched': opts.mark_watched,
         'merge_output_format': opts.merge_output_format,
-        'final_ext': opts.recodevideo or opts.remuxvideo or audio_ext,
+        'final_ext': final_ext,
         'postprocessors': postprocessors,
         'fixup': opts.fixup,
         'source_address': opts.source_address,
diff --git a/youtube_dlc/options.py b/youtube_dlc/options.py
index 06273c20a..a7c870171 100644
--- a/youtube_dlc/options.py
+++ b/youtube_dlc/options.py
@@ -18,14 +18,12 @@ from .utils import (
     get_executable_path,
     OUTTMPL_TYPES,
     preferredencoding,
+    REMUX_EXTENSIONS,
     write_string,
 )
 from .version import __version__
 
 
-_remux_formats = ('mp4', 'mkv', 'flv', 'webm', 'mov', 'avi', 'mp3', 'mka', 'm4a', 'ogg', 'opus')
-
-
 def _hide_login_info(opts):
     PRIVATE_OPTS = set(['-p', '--password', '-u', '--username', '--video-password', '--ap-password', '--ap-username'])
     eqre = re.compile('^(?P<key>' + ('|'.join(re.escape(po) for po in PRIVATE_OPTS)) + ')=.+$')
@@ -1042,7 +1040,7 @@ def parseOpts(overrideArguments=None):
             'Remux the video into another container if necessary (currently supported: %s). '
             'If target container does not support the video/audio codec, remuxing will fail. '
             'You can specify multiple rules; eg. "aac>m4a/mov>mp4/mkv" will remux aac to m4a, mov to mp4 '
-            'and anything else to mkv.' % '|'.join(_remux_formats)))
+            'and anything else to mkv.' % '|'.join(REMUX_EXTENSIONS)))
     postproc.add_option(
         '--recode-video',
         metavar='FORMAT', dest='recodevideo', default=None,
diff --git a/youtube_dlc/utils.py b/youtube_dlc/utils.py
index 79a0f6a63..f4ee52afb 100644
--- a/youtube_dlc/utils.py
+++ b/youtube_dlc/utils.py
@@ -1715,6 +1715,8 @@ KNOWN_EXTENSIONS = (
     'wav',
     'f4f', 'f4m', 'm3u8', 'smil')
 
+REMUX_EXTENSIONS = ('mp4', 'mkv', 'flv', 'webm', 'mov', 'avi', 'mp3', 'mka', 'm4a', 'ogg', 'opus')
+
 # needed for sanitizing filenames in restricted mode
 ACCENT_CHARS = dict(zip('ÂÃÄÀÁÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖŐØŒÙÚÛÜŰÝÞßàáâãäåæçèéêëìíîïðñòóôõöőøœùúûüűýþÿ',
                         itertools.chain('AAAAAA', ['AE'], 'CEEEEIIIIDNOOOOOOO', ['OE'], 'UUUUUY', ['TH', 'ss'],