Error/Warning - what's "prettier" way of achieving purpose

[ADFH]

Some code I've written has following line..

print   (!defined $DEBUG) ? $cgi_int->header : '' ;

Basically, if I'm debugging, a content type header is printed
elsewhere.. With the above line I get the following message:

"Useless use of a constant in void context"

Should I be using a full-blown if statement?
Should I be using a different way of saying null?
Is there a different structure I should be using?

ADFH