While testing out iostreams memory mapped file source I ran into an issue where it throws when opening a zero sized file (testing on windows 7 vc11 x64). for example something like: namespace io = boost::iostreams; namespace fs = boost::filesystem; fs::path path("C:\\boost\\boost_1_53_0\\libs\\context\\src\\dummy.cpp"); io::stream<io::mapped_file_source> file( path ); Will throw: failed create mapping: The volume for a file has been externally altered so that the opened file is no longer valid. From: http://tinyurl.com/cx2b9ru "When you do not want the size of the file to change (for example, when mapping read-only files), call CreateFileMapping and specify zero for both dwMaximumSizeHigh and dwMaximumSizeLow. Doing this creates a file mapping object that is exactly the same size as the file. Otherwise, you must calculate or estimate the size of the finished file because file mapping objects are static in size; once created, their size cannot be increased or decreased. An attempt to map a file with a length of zero in this manner fails with an error code of ERROR_FILE_INVALID. Programs should test for files with a length of zero and reject such files." I don't see anything in the docs that would lead me to believe this should throw. Rather I would expect: std::istream_iterator<char>(file) == std::istream_iterator<char>()