"error: ‘M_PIf’ was not declared in this scope"

when I try to build my application using “flatpak-builder build-dir org.flatpak.AWESOMEAPP”, I get this compilation error:

error: ‘M_PIf’ was not declared in this scope; did you mean ‘M_PI’?

M_PIf is defined in math.h inside a “#ifdef __USE_GNU”.

So I guess I need to install a Flatpak package to have access to this GNU extension but I do not know which one? Or maybe adding a specific compilation flag in CMakeLists.txt may help. Any idea? Thank you in advance.