Hello, I think in boost 1.34.0 the 64-bit for toolset=sun is missing. I'm using bjam to build boost. My environment: OS: Solaris 10 x86_64 (with latest patches) CC: Sun C++ 5.8 Patch 121018-10 2007/02/21 (Sun Studio 11 with latest patches) With 1.32.0 I have used the following command to build 64-bit binaries: tools/build/jam_src/bin/bjam -sHAVE_ICU=1 -sICU_PATH=$$PREFIX -sTOOLS=sunpro -d2 -j4 -sBUILD=debug\ "<instruction-set>athlon64" --prefix=$$PREFIX --includedir=$$PREFIX/include --libdir=$$PREFIX/lib/amd64 Now I'm using the following command to build boost: tools/jam/src/bin/bjam --v2 --toolset=sun stdlib=sun-stlport -d2 -j4 variant=debug --without-iostreams --without-python --without-regex --prefix=$$PREFIX --includedir=$$PREFIX/include --libdir=$$PREFIX/lib/amd64 I see no way (without patching tools/build/v2/tools/sun.jam) to get 64-bit binaries. Am I missing something?? Best regards, Markus