diff --git a/deploy/nginx/templates/contract-check-http.conf.template b/deploy/nginx/templates/contract-check-http.conf.template
index 943c682..78a9d48 100644
--- a/deploy/nginx/templates/contract-check-http.conf.template
+++ b/deploy/nginx/templates/contract-check-http.conf.template
@@ -18,6 +18,9 @@ client_max_body_size 50M;
 
 server {
     listen 80;
+    # IPv6 too — otherwise IPv6 clients fall through to nginx's stock
+    # default.conf server (static /usr/share/nginx/html → 404s).
+    listen [::]:80;
     server_name ${NGINX_SERVER_NAME};
 
     location ~ ^/(healthz|readyz|metrics|api/|admin/|docs|openapi.json) {