[Exim] exim4.20-2 + exiscan

I have a problem with compiling exim4.20-2 + exiscan:

awk '{ print ($1+1) }' cnumber.h > cnumber.temp
rm -f cnumber.h; mv cnumber.temp cnumber.h
gcc -c -O    version.c
version.c: In function `version_init':
version.c:43: `EXISCAN_VERSION' undeclared (first use in this function)
version.c:43: (Each undeclared identifier is reported only once
version.c:43: for each function it appears in.)
make[1]: *** [exim] Error 1
make[1]: Leaving directory `/root/sources/exim-4.20/build-Linux-i386'
make: *** [go] Error 2

Any hint?

Adam