When I do (for example) C:\Projects\boost-git\boost\tools\boostdep\build>b2 toolset=msvc-8.0 I get ...found 1 target... ...updating 1 target... msvc.write-setup-script C:\Users\PETERD~1\AppData\Local\Temp\b2_msvc_12.0_vcvarsall_x86.cmd ...updated 1 target... ...found 1 target... ...updating 1 target... msvc.write-setup-script C:\Users\PETERD~1\AppData\Local\Temp\b2_msvc_12.0_vcvarsall_x86_amd64.cmd ...updated 1 target... ...found 1 target... ...updating 1 target... msvc.write-setup-script C:\Users\PETERD~1\AppData\Local\Temp\b2_msvc_8.0_vcvarsall_x86.cmd ...updated 1 target... ...found 1 target... ...updating 1 target... msvc.write-setup-script C:\Users\PETERD~1\AppData\Local\Temp\b2_msvc_8.0_vcvarsall_x86_amd64.cmd ...updated 1 target... which correctly generates the setup scripts for the specified msvc-8.0, but also unconditionally generates the setup scripts for msvc-12.0, which are not needed at this time. This msvc-12.0 generation occurs even if I use a non-msvc toolset, or even just do b2 --show-libraries. C:\Projects\boost-git\boost>b2 --show-libraries ...found 1 target... ...updating 1 target... msvc.write-setup-script C:\Users\PETERD~1\AppData\Local\Temp\b2_msvc_12.0_vcvarsall_x86.cmd ...updated 1 target... ...found 1 target... ...updating 1 target... msvc.write-setup-script C:\Users\PETERD~1\AppData\Local\Temp\b2_msvc_12.0_vcvarsall_x86_amd64.cmd ...updated 1 target... The following libraries require building: - atomic - chrono [...]