In the most recent thread library changes from a day or so ago, the set_tss_data function was added to win32/thread.cpp. This function calls tss_cleanup_implemented to force some support for TSS cleanup to be present. Unfortunately, since set_tss_data is in the .cpp file (rather than being an inline function in a .hpp file) this requires tss_cleanup_implemented to always be present for WinThread versions of the static library, regardless of whether or not TSS is actually used. Since WinCE does not currently have a nifty automated way to clean up TSS in static builds, this means that there is always a link error when the static library is used (even when no TSS data is allocated). As an alternative, could the call to tss_cleanup_implemented() be moved to the thread_specific_ptr::reset() and thread_specific_ptr::release() functions in win32/tss.hpp, so that the link error only shows up if some TSS data is created? Incidentally, while looking through this, I had a question about src/tss_null.cpp. Does this file actually accomplish anything at the moment? It appears that it is intended to patch in an empty version of tss_cleanup_implemented() for WinThread builds when _MSC_VER is not defined. However, the #if block around the function definition includes the clause (defined(BOOST_THREAD_BUILD_LIB) || defined(BOOST_THREAD_TEST)). As far as I can tell, this file is not included in any static library build by thread/build/Jamfile.v2 and none of the test files declare BOOST_THREAD_TEST. So I'm not sure when this function definition would actually come into play. Just curious. Thanks, -Dave