Hello, After wrapping a simple C++ function of a double argument with boost python, I have noticed it crashes when called from Python with a numpy.int64 value. This is a likely situation, for example when evaluated for values from numpy.arange. Please see below for a minimum example. Is there some simple way of telling the wrapper how to handle numpy.int64 arguments? BTW, I have noticed that the boost/numpy library sets up several scalar converters on its initialization - this happens in boost/python/numpy.hpp <https://github.com/boostorg/python/blob/6f72675bff276599ffdccb9681018d8b2e36...> and then in the register_scalar_converters <https://github.com/boostorg/python/blob/6f72675bff276599ffdccb9681018d8b2e36...> function. However, adding a call to boost::python::numpy::initialize did not make a difference in my example. Thank you for any advice. Best, Pavol // dbfunction.cpp ------------------------------------------------------------ #include <boost/python/module.hpp> #include <boost/python/def.hpp> #include <boost/python/numpy.hpp> double duplicate(double x) { return 2 * x; } BOOST_PYTHON_MODULE(dbfunction) { using boost::python::def; // no difference with line below // boost::python::numpy::initialize(); def("duplicate", duplicate); } // --------------------------------------------------------------------------- # TEST $ python -c 'import dbfunction, numpy; dbfunction.duplicate(numpy.int64(0))' Traceback (most recent call last): File "<string>", line 1, in <module> Boost.Python.ArgumentError: Python argument types in dbfunction.duplicate(numpy.int64) did not match C++ signature: duplicate(double)