I fixed builds that attempted to use the -w option when calling perl. The shell was treating it as a single command name rather than a command with a switch. The easy way to fix this would be to do something similar to: ln -s ./perl 'perl -w' This will create a symbolic link named 'perl -w' allowing the build to work, in my case. I was running into this with trying to compile the library pango and it was annoying me, because I couldn't figure out where env was calling for the file 'perl -w' to change it. The -w switch only enables some additional warnings, so not entirely necessary. Another option might be to create a script named 'perl -w' then have it call perl with the -w switch.