I am trying to compile some code into a dynamic library and I am getting the following linker errors: Linking CXX shared library Bin/libLibTest.dylib xilibtool: executing 'libtool' ld: common symbols not allowed with MH_DYLIB output format with the - multi_module option CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem12initial_pathINS0_10basic_pathISbIwSt11char_tr aitsIwESaIwEENS0_12wpath_traitsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem12initial_pathINS0_10basic_pathISsNS0_11path_tr aitsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISbIwSt 11char_traitsIwESaIwEENS0_12wpath_traitsEEEEEmRKT_E7end_itr (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISsNS0_ 11path_traitsEEEEEmRKT_E7end_itr (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem12initial_pathINS0_10basic_pathISbIwSt11char_trai tsIwESaIwEENS0_12wpath_traitsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem12initial_pathINS0_10basic_pathISsNS0_11path_trai tsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISbIwSt11 char_traitsIwESaIwEENS0_12wpath_traitsEEEEEmRKT_E7end_itr (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISsNS0_11 path_traitsEEEEEmRKT_E7end_itr (size 16) libtool: internal link edit command failed make[2]: *** [Bin/libLibTest.dylib] Error 1 make[1]: *** [CMakeFiles/LibTest.dir/all] Error 2 make: *** [all] Err This is on OS X 10.4.11 with Intel C++ compiler version 10.1.007. Maybe I am not using the boost file_system library correctly? A simple reproducible case is to just try to create a library containing any code that includes boost/filesystem/operations.hpp. The same code works on gcc on OS X 10.4.11 (Xcode 2.5 tool set) Thanks -- Mike Jackson imikejackson & gmail * com