diff --git a/backup.sh b/backup.sh
index 29e6337..88d7383 100755
--- a/backup.sh
+++ b/backup.sh
@@ -55,10 +55,10 @@ do
     if [[ -f "${prefix}/incremental/${sql_item//:/.}.sql" ]]
     then
 	xsuffix=".diff"
-	${sqldump_prefix} ${sql_item//:/ } | diff ${prefix}/incremental/${sql_item//:/.}.sql - > ${prefix}/${stamp}/${sql_item//:/.}.sql.diff
+	${sqldump_prefix} ${sql_item//:/ } | rdiff delta ${prefix}/incremental/${sql_item//:/.}.sql.sign > ${prefix}/${stamp}/${sql_item//:/.}.sql.delta
     else
 	${sqldump_prefix} ${sql_item//:/ } | cat > ${prefix}/${stamp}/${sql_item//:/.}.sql
-	cp ${prefix}/${stamp}/${sql_item//:/.}.sql ${prefix}/incremental/
+	rdiff signature ${prefix}/${stamp}/${sql_item//:/.}.sql > ${prefix}/incremental/${sql_item//:/.}.sql.sign
     fi
     if [ "${do_quet}" == 0 ]
     then