false -Wmaybe-uninitialized?

[Anton Shterenlikht]

$ cat z.f90 
character(:), allocatable :: z
z = "mumu"
end

$ gfortran -Wall z.f90
z.f90:2:0:

 z = "mumu"
 ^
Warning: '.z' may be used uninitialized in this function [-Wmaybe-uninitialized]
$ 

Is this warning appropriate here?
Is this statement not initialisation?

Anton