Additional nginx directives - client_max_body_size issue

Hi,

I'm trying to add client_max_body_size to my site in Apache & nginx Settings under Additional nginx directives, but I'm getting an error:

Invalid nginx configuration: nginx: [emerg] "client_max_body_size" directive is duplicate in /var/www/vhosts/system/mysite.com/conf/vhost_nginx.conf:39 nginx: configuration file /etc/nginx/nginx.conf test failed

Any ideas on how to work around this?

Using Plesk 12.5 on Centos 7.