Problem with comma as separator when reading a boost multiprecision rational number

RatiionalReadingBug.cpp

#include <iostream>
#include <sstream>
#include <boost/multiprecision/cpp_int.hpp>
# include <boost/multiprecision/gmp.hpp>

int main(){
	//boost::multiprecision::cpp_rational   q;
	boost::multiprecision::mpq_rational q;
	
	std::istringstream is("5,600");

	is >> q;

	std::cout << q << std::endl;

    return 0;
}