A possibly more general fix would be to tell xgettext that fputs' argument is not c-format. That would catch all uses of fputs. Something like this:
--- po/Makevars~ 2012-05-10 11:05:30.000000000 +0200 +++ po/Makevars 2012-05-17 20:06:13.000000000 +0200 @@ -18,6 +18,7 @@ --flag=asprintf:2:c-format\ --flag=error:3:c-format\ --flag=error_at_line:5:c-format\ + --flag=fputs:1:no-c-format\ --flag=vasnprintf:3:c-format\ --flag=vasprintf:2:c-format\ --flag=verror:3:c-format\
