Make error (another one)

[Darkbartje]

while building i get an error:

....
zm_box.h: In method 'const class Coord Box::Centre() const':
zm_box.h:60: implicit declaration of function 'int round(...)'
make[2]: *** [zm_zone.o] Error 1
make[2]: Leaving directory '/root/zm-1.21.0/src'
etc....

Does anybody know what to do?
Thx

[zoneminder]

This was an issue in 1.20.0, it should be ok in 1.21.1

Phil