diff --git a/youtube_dl/options.py b/youtube_dl/options.py
index 0a0641bd4..91c0fbc02 100644
--- a/youtube_dl/options.py
+++ b/youtube_dl/options.py
@@ -434,7 +434,7 @@ def parseOpts(overrideArguments=None):
     subtitles.add_option(
         '--all-subs',
         action='store_true', dest='allsubtitles', default=False,
-        help='Download all the available subtitles of the video')
+        help='Write subtitle files of all available languages for the video (format follows --sub-format)')
     subtitles.add_option(
         '--list-subs',
         action='store_true', dest='listsubtitles', default=False,