diff --git a/doc/ffmpeg-doc.texi b/doc/ffmpeg-doc.texi
index ffa3b5b447..68b56d4522 100644
--- a/doc/ffmpeg-doc.texi
+++ b/doc/ffmpeg-doc.texi
@@ -44,14 +44,14 @@ standard mixer.
 FFmpeg can grab the X11 display.
 
 @example
-ffmpeg -f x11grab -i :0.0 /tmp/out.mpg
+ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg
 @end example
 
 0.0 is display.screen number of your X11 server, same as
 the DISPLAY environment variable.
 
 @example
-ffmpeg -f x11grab -i :0.0+10,20 /tmp/out.mpg
+ffmpeg -f x11grab -s cif -i :0.0+10,20 /tmp/out.mpg
 @end example
 
 0.0 is display.screen number of your X11 server, same as the DISPLAY environment