diff --git a/update-dns.sh b/update-dns.sh
index e041a8d..ecfbd63 100755
--- a/update-dns.sh
+++ b/update-dns.sh
@@ -1,5 +1,8 @@
 #! /usr/bin/env bash
 
+# PID file
+PID_FILE="/run/ffhb-update-dns.pid"
+
 # getting workingdir of scripts
 WORK_DIR="$(dirname $(readlink -nf $0))"
 
@@ -22,13 +25,21 @@ fi
 ZONEFILE=/var/cache/bind/ffhb.nodes.zone
 RZONEFILE=/var/cache/bind/arpa.ip6.f.d.2.f.5.1.1.9.0.f.2.c.zone
 
+# write run file
+if [ -f "$PID_FILE" ]; then
+  echo "Script already running!" >&2
+  exit 1
+else
+  touch "$PID_FILE"
+fi
+
 # loop until data received
 while true; do
   # increment counter
   NUM=$(($NUM+1))
 
   # get data from alfred
-  alfred-json -z -r 158 > "$TMP_FILE" 2>/dev/null
+  timeout -s KILL 30s alfred-json -z -r 158 >"$TMP_FILE" 2>/dev/null
 
   # on success leave loop
   if [ $? -eq 0 ]; then
@@ -54,7 +65,7 @@ if zonegen.py < "$TMP_FILE" > "${ZONEFILE}.new"; then
 fi
 
 # generate reverse zone
-if rzonegen.py 0.0.0.0.c.2.f.0.9.1.1.5.f.2.d.f.ip6.arpa < "$TMP_FILE" > "${RZONEFILE}.new"; then
+if rzonegen.py 0.0.0.0.c.2.f.0.9.1.1.5.f.2.d.f.ip6.arpa <"$TMP_FILE" >"${RZONEFILE}.new"; then
   mv "${RZONEFILE}.new" "${RZONEFILE}"
 fi
 
@@ -63,3 +74,6 @@ rndc reload >/dev/null
 
 # remove tmp file
 rm -f "$TMP_FILE"
+
+# remove PID file
+rm -f "$PID_FILE"