diff --git a/ldiskfs/configure.ac b/ldiskfs/configure.ac
index b004238316b099f5e0d5781660878e1eeb646652..808ca1c1dde247a3a90ca5fc5cbe56665f252784 100644
--- a/ldiskfs/configure.ac
+++ b/ldiskfs/configure.ac
@@ -95,6 +95,7 @@ case $LINUXRELEASE in
 2.6.15*) LDISKFS_SERIES="2.6-fc5.series";;
 2.6.16*) LDISKFS_SERIES="2.6-sles10.series";;
 2.6.18-*el5*) LDISKFS_SERIES="2.6-rhel5.series";;
+2.6.18-*prep*) LDISKFS_SERIES="2.6-rhel5.series";;
 2.6.18*) LDISKFS_SERIES="2.6.18-vanilla.series";;
 *) AC_MSG_WARN([Unknown kernel version $LINUXRELEASE, fix ldiskfs/configure.ac])
 esac