undefined reference to 'do_varargs'

[Jiezen]

When I try to build my DLL with win32ada 2017, it issues an error :

gnatlink <ali\file> -o <jnk\file> -mdll -Wl,base-file,<base\file>
win32-winuser.o:win32-winuser.adb:(.text+0xa62): undefined reference to 'do_varargs' 
win32-winuser.o:win32-winuser.adb:(.text+0x15be): undefined reference to 'do_varargs' 
collect2.exe: error: ld returned 1 exit status
gnatlink: error when calling C:\GNAT\2017\bin\gcc.exe

Do you know why gnatlink issues this error ?