amavisd-0.1 make error: `bool' previously declared here

[Vincenzo M. <vin...@re...>]

environment:
------------
Linux servermail.regione.toscana.it 2.4.21-37.ELsmp #1 SMP Wed Sep 7 
13:28:55 EDT 2005 i686 i686 i386 GNU/Linux

sendmail Version 8.13.6

amavisd-0.1
------------

on the server, just operative (amavisd-0.1 compiled last time with 
sendmail-8.12.10 without error), i have added clamav; then i must 
recompile amavis to activate clamav support

configure step is OK and it ends without error; but make gives this message

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gcc -DHAVE_CONFIG_H -I. -I. -I.. 
-I/usr/local/src/sendmail-8.13.6/include  -g -O2 -pthread -c `test -f 
amavis-milter.c || echo './'`amavis-milter.c
amavis-milter.c:58: redefinition of `bool'
/usr/local/src/sendmail-8.13.6/include/libmilter/mfapi.h:84: `bool' 
previously declared here
------------------

someone has had the same problem?
below the complete log...

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[root@servermail amavisd-0.1]# make
make  all-recursive
make[1]: Entering directory `/usr/local/src/amavisd-0.1'
Making all in amavis
make[2]: Entering directory `/usr/local/src/amavisd-0.1/amavis'
source='amavis-milter.c' object='amavis-milter.o' libtool=no \
depfile='.deps/amavis-milter.Po' tmpdepfile='.deps/amavis-milter.TPo' \
depmode=gcc3 /bin/sh ../depcomp \
gcc -DHAVE_CONFIG_H -I. -I. -I.. 
-I/usr/local/src/sendmail-8.13.6/include  -g -O2 -pthread -c `test -f 
amavis-milter.c || echo './'`amavis-milter.c
amavis-milter.c:58: redefinition of `bool'
/usr/local/src/sendmail-8.13.6/include/libmilter/mfapi.h:84: `bool' 
previously declared here
make[2]: *** [amavis-milter.o] Error 1
make[2]: Leaving directory `/usr/local/src/amavisd-0.1/amavis'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/usr/local/src/amavisd-0.1'
make: *** [all] Error 2
[root@servermail amavisd-0.1]#
------------------