I see that there is now emscripten support in boost build but it doesn't seem to work for me. After installing emscripten on Windows, adding using emscripten ; in my site-config.jam, then running b2 from the emscripten command prompt, I get the output below. Any help greatly appreciated! Emil boost-build/src/build\property.jam:743: in class@property-map.find from module object(property-map)@26 error: Ambiguous key boost-build/src/build\type.jam:333: in generated-target-ps from module type boost-build/src/build\type.jam:270: in type.generated-target-suffix from module type boost-build/src/build\virtual-target.jam:509: in virtual-target.add-prefix-and-suffix from module virtual-target boost-build/src/build\virtual-target.jam:468: in _adjust-name from module object(file-target)@3764 boost-build/src/build\virtual-target.jam:253: in abstract-file-target.__init__ from module object(file-target)@3764 boost-build/src/build\virtual-target.jam:561: in class@file-target.__init__ from module object(file-target)@3764 boost-build/src/kernel\class.jam:90: in class.new from module class boost-build/src/build\generators.jam:558: in generated-targets from module object(C-compiling-generator)@138 boost-build/src/build\generators.jam:453: in construct-result from module object(C-compiling-generator)@138 boost-build/src/build\generators.jam:412: in run-really from module object(C-compiling-generator)@138 boost-build/src/build\generators.jam:386: in class@generator.run from module object(C-compiling-generator)@138 boost-build/src/build\generators.jam:994: in try-one-generator-really from module generators boost-build/src/build\generators.jam:1056: in try-one-generator from module generators boost-build/src/build\generators.jam:1294: in construct-really from module generators boost-build/src/build\generators.jam:1378: in generators.construct from module generators boost-build/src/build\targets.jam:1553: in construct from module object(typed-target)@3554 boost-build/src/build\targets.jam:1353: in class@basic-target.generate from module object(typed-target)@3554 boost-build/src/build\targets.jam:774: in generate-really from module object(main-target)@3735 boost-build/src/build\targets.jam:746: in class@main-target.generate from module object(main-target)@3735 boost-build/src/build\targets.jam:895: in targets.generate-from-reference from module targets boost-build/src/build\targets.jam:1266: in generate-dependencies from module object(typed-target)@2173 boost-build/src/build\targets.jam:1323: in class@basic-target.generate from module object(typed-target)@2173 boost-build/src/build\targets.jam:774: in generate-really from module object(main-target)@2988 boost-build/src/build\targets.jam:746: in class@main-target.generate from module object(main-target)@2988 boost-build/src\build-system.jam:714: in load from module build-system NT\..\..\munch\boost-build\src\kernel\modules.jam:295: in import from module modules NT\..\..\munch\boost-build\src\kernel\bootstrap.jam:139: in boost-build from module NT\..\..\munch\boost-build.jam:6: in module scope from module