diff --git a/tools/rel.sh b/tools/rel.sh
index 2079c7052..466b1f485 100755
--- a/tools/rel.sh
+++ b/tools/rel.sh
@@ -2,6 +2,6 @@
 
 from=${1}
 to=${2}
-common=`printf '%s\0%s' "${from}" "${to}" | sed 's/\(.*\).*\x0\1.*/\1/' | sed 's@/[^/]*$@/@'`
+common=`printf '%s\n%s' "${from}" "${to}" | sed 'N;s/\(.*\).*\n\1.*$/\1/' | sed 's@/[^/]*$@/@'`
 prefix=`printf '%s\n' ${from#$common} | sed 's@[^/][^/]*@..@g'`
 printf '%s\n' "$prefix/${to#$common}"