Slony-I Version with Postgres 8.4.0

What version of Slony-I is "ok" to use with version 8.4.0, I am getting this error when trying to make against 8.4.0 on
RHEL4:

[postgres@linux1558 slony1-1.2.15]$ make
make[1]: Entering directory `/home/postgres/slony1-1.2.15/src'
make[2]: Entering directory `/home/postgres/slony1-1.2.15/src/xxid'
gcc -g -O2 -Wall -Wmissing-prototypes -Wmissing-declarations -fpic -I../.. -I/usr/local/pgsql/include/
-I/usr/local/pgsql/include/server/ -c -o xxid.o xxid.c 
xxid.c: In function `_Slony_I_getMinXid':
xxid.c:236: error: `SerializableSnapshot' undeclared (first use in this function)
xxid.c:236: error: (Each undeclared identifier is reported only once
xxid.c:236: error: for each function it appears in.)
xxid.c: In function `_Slony_I_getMaxXid':
xxid.c:249: error: `SerializableSnapshot' undeclared (first use in this function)
make[2]: *** [xxid.o] Error 1
make[2]: Leaving directory `/home/postgres/slony1-1.2.15/src/xxid'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/postgres/slony1-1.2.15/src'
make: *** [all] Error 2