diff --git a/youtube_dl/postprocessor/embedthumbnail.py b/youtube_dl/postprocessor/embedthumbnail.py
index 3990908b6..c854cb541 100644
--- a/youtube_dl/postprocessor/embedthumbnail.py
+++ b/youtube_dl/postprocessor/embedthumbnail.py
@@ -17,6 +17,7 @@ from ..utils import (
     shell_quote
 )
 
+from base64 import b64encode
 
 class EmbedThumbnailPPError(PostProcessingError):
     pass
@@ -124,7 +125,38 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
             else:
                 os.remove(encodeFilename(filename))
                 os.rename(encodeFilename(temp_filename), encodeFilename(filename))
+
+        elif info['ext'] in ['opus', 'ogg', 'flac']:
+            try:
+                from mutagen.oggvorbis import OggVorbis
+                from mutagen.oggopus   import OggOpus
+                from mutagen.flac      import Picture, FLAC
+            except ImportError:
+                raise EmbedThumbnailPPError('mutagen was not found. Please install.')
+
+            # to prevent the behaviour of in-place modification of Mutagen
+            shutil.copyfile(filename, temp_filename)
+
+            aufile = {'opus': OggOpus, 'flac': FLAC, 'ogg', OggVorbis}[info['ext']](temp_filename)
+
+            covart = Picture()
+            covart.data = open(thumbnail_filename, 'rb').read()
+            covart.type = 3  # as the front cover
+
+            if info['ext'] == 'flac':
+                aufile.add_picture(covart)
+            else:
+                # https://wiki.xiph.org/VorbisComment#METADATA_BLOCK_PICTURE
+                aufile['metadata_block_picture'] = b64encode(covart.write()).decode('ascii')
+
+            self._downloader.to_screen('[mutagen] Adding thumbnail to "%s"' % temp_filename)
+            aufile.save()
+            
+            if not self._already_have_thumbnail:
+                os.remove(encodeFilename(thumbnail_filename))
+            os.remove(encodeFilename(filename))
+            os.rename(encodeFilename(temp_filename), encodeFilename(filename))
         else:
-            raise EmbedThumbnailPPError('Only mp3 and m4a/mp4 are supported for thumbnail embedding for now.')
+            raise EmbedThumbnailPPError('Only mp3, m4a/mp4, ogg, opus and flac are supported for thumbnail embedding for now.')
 
         return [], info