diff --git a/ffmpeg.c b/ffmpeg.c
index 44a84ad3d1b73f05227ef2727e60e4995969b432..3f8fada45f41958e652b4143c602869c4090d849 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -3950,7 +3950,7 @@ const OptionDef options[] = {
     { "g", HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)opt_gop_size}, "set the group of picture size", "gop_size" },
     { "intra", OPT_BOOL | OPT_EXPERT | OPT_VIDEO, {(void*)&intra_only}, "use only intra frames"},
     { "vn", OPT_BOOL | OPT_VIDEO, {(void*)&video_disable}, "disable video" },
-    { "vdt", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&video_discard}, "discard threshold" },
+    { "vdt", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&video_discard}, "discard threshold", "n" },
     { "qscale", HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)opt_qscale}, "use fixed video quantiser scale (VBR)", "q" },
     { "qmin", HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)opt_qmin}, "min video quantiser scale (VBR)", "q" },
     { "qmax", HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)opt_qmax}, "max video quantiser scale (VBR)", "q" },