[ros-users] how to "rosparam set" with a negative number?

Maybe I'm overlooking something obvious here, but this fails:

$ rosparam set /longitude -97.728524
Usage: rosparam set [options] parameter value

rosparam: error: no such option: -9

Is there some trick? Quoting does not help.

I can rosparam load the value from a YAML file, but I still wonder how
to do it from the command line.
--
joq