This is my system: Main memory size: 3941 Mbytes 2 AuthenticAMD AMD Athlon(tm) 64 X2 Dual Core Processor 4600+ processors MHz 2400.000 512 kB cache 1 vga+ graphics device 1 Quadro FX 540 graphics device 1 IDE device: /dev/hdc: ATAPI 40X DVD-ROM drive, 254kB Cache, UDMA(33) PCI bus devices: 20 generic devices I'm trying to get started with gcc. I installed from source, I didn't get any errors. I started by trying out this program from Programming in Objective-C: // First program example #import <stdio.h> int main (int argc, const char *argv[]) { printf ("Programming is fun.\n"); return 0; } I compiled this way: ~/Applications/gcc/bin/gcc main.m -o prog1 -l objc when I run prog1 I get : ./prog1: error while loading shared libraries: libobjc.so.1: wrong ELF class: ELFCLASS32 My installation is as follows, ./gcc -v reports: Using built-in specs. Target: x86_64-unknown-linux-gnu Configured with: /usr/people/stevenq/src/gcc-4.1.2/configure --prefix=/usr/people/stevenq/Applications/gcc Thread model: posix gcc version 4.1.2 So it knows it's 64 bit, My LD_LIBRARY_PATH has /usr/people/stevenq/Applications/gcc/lib in it. Any reason why it's using a 32 bit library, did it somehow compiled with 32 bit? Best regards, Steven