erf and erfc warnings

When I compile the Radiance suite using VS2013 on Windows, I get a bunch of
warnings like the following:

d:\nljones\radiance\src\common\rtmath.h(50): warning C4273: 'erf' :
inconsistent dll linkage
          C:\Program Files (x86)\Microsoft Visual Studio
12.0\VC\include\math.h(486) : see previous definition of 'erf'
d:\nljones\radiance\src\common\rtmath.h(51): warning C4273: 'erfc' :
inconsistent dll linkage
          C:\Program Files (x86)\Microsoft Visual Studio
12.0\VC\include\math.h(487) : see previous definition of 'erfc'

It looks to me like the functions erf and erfc are declared both in math.h
and rtmath.h, so the compiler isn't sure which one to use. Does anyone know
which error function definition is being used?

Thanks,

Nathaniel