Hi, I am trying to use Boost.Units to convert between different units. I have implemented the example code for the "Radar Beam Height" [1] section but trying to convert between nautical mile and imperial foot result in a compiler error: I have: typedef boost::units::quantityboost::units::si::length Meters; typedef boost::units::quantityimperial::length Feet; typedef boost::units::quantitynautical::length NMiles; double func() { // Working const Meters si1(300.0*nautical::miles); const Meters si2(300.0*imperial::feet); const Feet feet1(300.0*imperial::feet); const Feet feet2(300.0*boost::units::si::meters); const NMiles mile1(300.0*nautical::miles); const NMiles mile2(300.0*boost::units::si::meters); // BROKEN const Feet feet3(300.0*nautical::miles); const NMiles mile3(300.0*imperial::feet); } The first few works, converting between meters and the new units, but converting between the two does not work. To see the issue see the code on Compiler Explorer here: https://gcc.godbolt.org/z/MpvuMy How can I get this working? [1] https://www.boost.org/doc/libs/1_68_0/doc/html/boost_units/Examples.html#boo... Regards,