Hello, I tried the new dynamic_bitset primarily because of the find_first/next thing but ran into trouble with multiple definitions of count_table<true>::table. The appended example files compile flawlessly with dynamic_bitset in boost-1.31 but raises link error with the new one: $ g++ --version g++ (GCC) 3.3.3 $ g++ main.cpp filea.cpp -o dynbitsettest /tmp/ccgBA6cl.o(.rodata+0x0): multiple definition of `boost::detail::dynamic_bitset_count_impl::count_table<(bool)1>::table' /tmp/ccoabDBm.o(.rodata+0x0): first defined here collect2: ld returned 1 exit status -- Viktor #ifndef AGUARD_H_ #define AGUARD_H_ #include <boost/dynamic_bitset.hpp> class A { public: void do_dummy(); protected: boost::dynamic_bitset<> m_bitset; }; #endif