Installed coreutils on CentOS for sort --human-readable flag but it still doesn't work

I'm trying to do du -h | sort -h , but my CentOS 5.7 doesn't have -h flag for sort. So I installed coreutils

Updated:    
  coreutils.x86_64 0:5.97-34.el5_8.1
Complete!

yet sort still doesn't have the -h flag. Am I not doing something,or doing something wrong? I'm fairly new to *nix.