diff --git a/Containers/mastercontainer/daily-backup.sh b/Containers/mastercontainer/daily-backup.sh
index 3b2d053a..f87b3966 100644
--- a/Containers/mastercontainer/daily-backup.sh
+++ b/Containers/mastercontainer/daily-backup.sh
@@ -16,7 +16,7 @@ fi
 sudo -u www-data touch "/mnt/docker-aio-config/data/daily_backup_running"
 
 # Check if apache is running/stopped, watchtower is stopped and backupcontainer is stopped
-APACHE_PORT="$(docker inspect nextcloud-aio-apache --format "{{.HostConfig.PortBindings}}" | grep -oP '[0-9]+' | head -1)"
+APACHE_PORT="$(docker inspect nextcloud-aio-apache --format "{{.HostConfig.PortBindings}}" | grep -o '[0-9]\+' | head -1)"
 while docker ps --format "{{.Names}}" | grep -q "^nextcloud-aio-apache$" && ! nc -z nextcloud-aio-apache "$APACHE_PORT"; do
     echo "Waiting for apache to become available"
     sleep 30