"fastcgi_cache_purge" directive is incompatible with "fastcgi_cache"

I've added the following to my nginx config:

  location ~ /purge(/.*) {
    allow 127.0.0.1;
    allow 10.10.0.0/16;
    include includes/public-cache.conf;
    fastcgi_cache_purge CACHE_PUB $public_cache_key;
  }

The .conf included in the above loads config such as:

fastcgi_cache CACHE_PUB;

fastcgi_cache_methods GET HEAD POST;

map $request_uri $public_cache_key {
    default $scheme$request_method$host$request_uri;
}
...<other params truncated>...

fastcgi_cache_path /var/www/site/cache/nginx levels=1:2 keys_zone=CACHE_PUB:200m inactive=168h;

When starting nginx:

nginx: [emerg] "fastcgi_cache_purge" directive is incompatible with "fastcgi_cache" in /etc/nginx/conf.d/site.conf:12

# Line 12 being " fastcgi_cache_purge" line.

nginx -V output

nginx version: nginx/1.14.2
built by gcc 6.3.0 20170516 (Debian 6.3.0-18+deb9u1)
built with OpenSSL 1.1.0f  25 May 2017 (running with OpenSSL 1.1.0j  20 Nov 2018)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-g -O2 -fdebug-prefix-map=/data/builder/debuild/nginx-1.14.2/debian/debuild-base/nginx-1.14.2=. -specs=/usr/share/dpkg/no-pie-compile.specs -fstack-protector-strong -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fPIC' --with-ld-opt='-specs=/usr/share/dpkg/no-pie-link.specs -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -pie'

FRiCKLE / ngx_cache_purge

"fastcgi_cache_purge" directive is incompatible with "fastcgi_cache" #69