Como você está definindo "totalmente" 64 bits?
% file /usr/bin/perl
/usr/bin/perl: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [i386:Mach-O executable i386]
/usr/bin/perl (for architecture x86_64): Mach-O 64-bit executable x86_64
/usr/bin/perl (for architecture i386): Mach-O executable i386
% sw_vers
ProductName: Mac OS X
ProductVersion: 10.13.5
BuildVersion: 17F77