command line - Using ffmpeg to cut up video

I am using ffmpeg to cut out a section of a large file like this:

ffmpeg -i input.wmv -ss 60 -t 60 -acodec copy -vcodec copy output.wmv

The -ss part works fine but the -t is ignored. It correctly removes the initial specified seconds specified with -ss but then keeps going to the end of the input with the copy.

Is there a way to use ffmpeg to cut off the end of a video without recoding it?