I' stuck with this strange issue with boost thread 1.48 when compiling this minimal example: #include <boost/thread/thread.hpp> int main() { retun 0; } with gcc -v Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.5-8' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --with-arch-32=i586 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix I get this error, .. I can't find anything via google… /usr/local/include/boost/thread/pthread/condition_variable.hpp: In member function ‘void boost::condition_variable::wait(boost::unique_lock<boost::mutex>&)’: /usr/local/include/boost/thread/pthread/condition_variable.hpp:53: error: ‘internal_mutex’ was not declared in this scope