Undefined reference to: Arith::mpmod

[Smoke]

This error has recently appeared
undefined reference to `libbase::Arith::mpmod(std::vector<unsigned char, std::allocator<unsigned char> > const&, std::vector<unsigned char, std::allocator<unsigned char> > const&)'

struct Arith{
bigint operator%(const bigint& x) const {
		bigint r;
		libbase::Arith ar;
		r.value = ar.mpmod(value, x.value); // Error caused here
		return r;
	}
}

Prototype

	std::vector<unsigned char> mpmod(const std::vector<unsigned char>& u,
			const std::vector<unsigned char>& v);

	std::vector<unsigned char> mpmod(std::vector<unsigned char>& u,
			std::vector<unsigned char>& v);

std::vector<unsigned char> Arith::mpmod(const std::vector<unsigned char>& u,
		const std::vector<unsigned char>& v) {

	std::vector<unsigned char> w = mpdiv(u, v);
	w = mpmul(w, v);
	return mpsub(u, w);//mpmul(w, v));
}


std::vector<unsigned char> Arith::mpmod(std::vector<unsigned char>& u,
		const std::vector<unsigned char>& v) {

	std::vector<unsigned char> w = mpdiv(u, v);
	w = mpmul(w, v);
	return mpsub(u, w);//mpmul(w, v));
}