You'll have to figure out where in Net::Printer it is inheriting the tainted data, as it is not from your calls to the Net::Printer methods-- I assume you are untainting things before you use them. Probably Net::Printer is using an environement variable or two. You have then three choices, either set the specific $ENV{key} from within your script, or auto-detaint all $ENV{keys} using the methods shown in the other writeups in this node wrapped in foreach my $key (keys %ENV) {...} , or rewrite the module to be taint-safe.