Do you get the same result if you put the include path on the command line, like this? "b2 address-model=64 include=D:\icu\include"
Thanks Erik. With this information I was able to get closer. My b2 command line now is: b2 address-model=64 include="D:\icu\include" library-path="D:\icu\lib64" -sICU_PATH="D:\icu" cxxstd=20 and the has_icu build is failing because it can't find icuind.lib. I believe that's a debug version of the icuin.lib and it looks like the binary distribution of the ICU library doesn't include any debug builds. If I add the "variant=release" option to my b2 command line, it finds icu: - icu : yes [2] - iconv (libc) : no [2] - iconv (separate) : no [2] So I guess I have to take a step back and build ICU first. I remember that being tricky and was hoping to avoid it. Cory