Thank you very much James. The prob is i was using MacPython wich installs in /Library/Frameworks/ PyhonFrameworks and does not build in 64bit macports python is only 64bit when i know run the test i get test_wrapper.py Segmentation fault Maybe i should recapitulate for SnowLeopard: make sure /System/Library/Frameworks/Python.framework/ python is used or that that file which python outputs 3 architectures /usr/bin/python: Mach-O universal binary with 3 architectures /usr/bin/python (for architecture x86_64): Mach-O 64-bit executable x86_64 /usr/bin/python (for architecture i386): Mach-O executable i386 /usr/bin/python (for architecture ppc7400): Mach-O executable ppc build boost 1.40 by first vim tools/build/v2/tools/gcc.jam , :set number , :+378, replace 378 option = -m64 ; by 378 if $(model) = 32_64 379 { 380 } 381 else 382 { 383 option = -m64 ; 384 } build with sudo ./bjam -j4 variant=release link=shared architecture=x86 address-model=32_64 install