[Boost-users] [Units] conversion between double and millimeter

Hello Boost.Units users, When I convert a double to a unit (e.g. meter) and back, this works as expected. When I convert a double to a prefixed unit (e.g. millimeter) and back, this fails to compile. The code below shows how I'd expect it to work. What do I overlook? Thanks, Richel Bilderbeek const double x_in_mm = 1.0; const Length x(x_in_mm * milli * meter); //This works as expected: const double x_again_in_m = x / meter; //Why doesn't this: const double x_again_in_mm = x / (milli * meter); //Fails