Hello. Unlike previous versions which are named with underscores only, the boost 1.56 b1 tarball is named boost-1_56_0_b1.{zip, tar.gz, tar.bz, 7z}. Unpacking the tarball creates a boost-1_56_0_b1 directory instead of the expected one boost_1_56_0_b1 See also: http://sourceforge.net/projects/boost/files/boost/1.56.0.beta.1/ http://sourceforge.net/projects/boost/files/boost/1.55.0/ http://sourceforge.net/projects/boost/files/boost/1.54.0/ http://sourceforge.net/projects/boost/files/boost/1.53.0/ (older versions also follow the underscore filename pattern). Is there any particular reason for doing this? I suspect that it might cause problems to scripts looking for a specific pattern for the boost tar file and/or directory. All the best, - m.