man -m: Bad argument

[Jan Stary]

I have some man pages installed in $HOME/man
so I ugment my manpath like this in my ~/.shrc

  test -d $HOME/man && alias man="man -m $HOME/man"

Now man(1) complains saying

  $ man ls
  man: -m/home/hans/man: Bad argument

Using "$HOME/man/" or "$HOME/man:" results in the same.

Am I missing something obvious?

        Jan