Image Magick: resize and fill doesn't work

this is what I'm doing:

convert input.png -fill white -resize 2480x3508^ out.png

and I get:

convert: invalid argument for option `2480x3508^': -resize.

Version: ImageMagick 6.2.8 06/11/08 Q16 http://www.imagemagick.org

The error doesn't present itself if the '^' at the end of the Geometry argument is removed.

The Fill Area Flag (^) is available from ImageMagick v6.3.8-3 onwards. For further reference and an alternative for older versions, please check the following link.

http://www.imagemagick.org/Usage/resize/#space_fill