diff --git a/docker-compose.yml b/docker-compose.yml
index 614a98b..ed438f6 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -10,10 +10,11 @@ services:
       - zammad-postgresql
     entrypoint: /usr/local/bin/backup.sh
     environment:
-      - BACKUP_SLEEP=86400
+      - BACKUP_TIME=03:00
       - HOLD_DAYS=10
       - POSTGRESQL_USER=${POSTGRES_USER}
       - POSTGRESQL_PASSWORD=${POSTGRES_PASS}
+      - TZ=Europe/Berlin
     image: postgres:${POSTGRES_VERSION}
     restart: ${RESTART}
     volumes:
diff --git a/scripts/backup.sh b/scripts/backup.sh
index 3874ed6..9821c18 100755
--- a/scripts/backup.sh
+++ b/scripts/backup.sh
@@ -11,7 +11,7 @@ set -e
 : "${POSTGRESQL_DB:=zammad_production}"
 
 function check_railsserver_available {
-  until (echo > /dev/tcp/${ZAMMAD_RAILSSERVER_HOST}/${ZAMMAD_RAILSSERVER_PORT}) &> /dev/null; do
+  until (echo > "/dev/tcp/$ZAMMAD_RAILSSERVER_HOST/$ZAMMAD_RAILSSERVER_PORT") &> /dev/null; do
     echo "waiting for railsserver to be ready..."
     sleep 60
   done
@@ -43,10 +43,15 @@ if [ "$1" = 'zammad-backup' ]; then
   check_railsserver_available
 
   while true; do
+    NOW_TIMESTAMP=$(date +%s)
+    TOMORROW_DATE=$(date -d@"$((NOW_TIMESTAMP + 24*60*60))" +%Y-%m-%d)
+    
     zammad_backup
 
-    # wait until next backup
-    sleep "${BACKUP_SLEEP}"
+    NEXT_TIMESTAMP=$(date -d "$TOMORROW_DATE $BACKUP_TIME" +%s)
+    NOW_TIMESTAMP=$(date +%s)
+
+    sleep $((NEXT_TIMESTAMP - NOW_TIMESTAMP))
   done
 fi