SPI_GETWALLPAPER constant for SystemParametersInfo API function

According to the MSDN Library (July 2001) it is possible to get the path of
the desktop wallpaper (in Win2K or later) using the SystemParametersInfo
function setting the SPI_GETDESKWALLPAPER constant as the uiAction (first)
parameter.
I tried to use that function but the compiler tells me that SPI_GETDESKWALLPAPER
is not defined and certainly it is is not declared in the Winuser.h file.
Can anyone please tell me the value of that constant so I can define it in
my project?

Thanks a lot!