diff --git a/Dockerfile b/Dockerfile
index acaf6c779..40d18c98d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -42,6 +42,8 @@ ENV PORT= \
     TZ=UTC \
     SERVER_DESCRIPTION= \
     BACKUP_ENABLED=true \
+    DELETE_OLD_BACKUPS=false \
+    OLD_BACKUP_DAYS=30 \
     BACKUP_CRON_EXPRESSION="0 0 * * *" \
     AUTO_UPDATE_ENABLED=false \
     AUTO_UPDATE_CRON_EXPRESSION="0 * * * *" \
diff --git a/scripts/backup.sh b/scripts/backup.sh
index 0fd0b6d65..3f7c845fd 100644
--- a/scripts/backup.sh
+++ b/scripts/backup.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 if [ "${RCON_ENABLED}" = true ]; then
-        rcon-cli -c /home/steam/server/rcon.yaml save
+    rcon-cli -c /home/steam/server/rcon.yaml save
 fi
 
 DATE=$(date +"%Y-%m-%d_%H-%M-%S")
@@ -11,12 +11,18 @@ cd /palworld/Pal/ || exit
 tar -zcf "$FILE_PATH" "Saved/"
 
 if [ "$(id -u)" -eq 0 ]; then
-        chown steam:steam "$FILE_PATH"
+    chown steam:steam "$FILE_PATH"
 fi
 
 echo "backup created at $FILE_PATH"
 
 if [ "${DELETE_OLD_BACKUPS}" = true ]; then
-        echo "removing backups older than ${OLD_BACKUP_DAYS:=30} days"
-        find /palworld/backups/ -mindepth 1 -maxdepth 1 -mtime "+${OLD_BACKUP_DAYS}" -print -delete
+    if [ -z "${OLD_BACKUP_DAYS}" ]; then
+        echo "Unable to deleted old backups, OLD_BACKUP_DAYS is empty."
+    elif [[ "${OLD_BACKUP_DAYS}" =~ ^[0-9]+$ ]]; then
+        echo "removing backups older than ${OLD_BACKUP_DAYS} days"
+        find /palworld/backups/ -mindepth 1 -maxdepth 1 -mtime "+${OLD_BACKUP_DAYS}" -type f -name 'palworld-save-*.tar.gz' -print -delete
+    else
+        echo "Unable to deleted old backups, OLD_BACKUP_DAYS is not an integer. OLD_BACKUP_DAYS=${OLD_BACKUP_DAYS}"
+    fi
 fi