diff --git a/deploy/nginx-contracts.conf b/deploy/nginx-contracts.conf
index e4b83ab..efb16a8 100644
--- a/deploy/nginx-contracts.conf
+++ b/deploy/nginx-contracts.conf
@@ -44,10 +44,13 @@ server {
     }
 
     location /upload {
-        add_header Access-Control-Allow-Origin "*";
-        add_header Access-Control-Allow-Methods "POST, OPTIONS";
-        add_header Access-Control-Allow-Headers "*";
-        if ($request_method = OPTIONS) { return 204; }
+        if ($request_method = OPTIONS) {
+            add_header Access-Control-Allow-Origin "*";
+            add_header Access-Control-Allow-Methods "POST, OPTIONS";
+            add_header Access-Control-Allow-Headers "*";
+            add_header Content-Length 0;
+            return 204;
+        }
         proxy_pass http://127.0.0.1:8766;
         proxy_read_timeout 300s;
         client_max_body_size 100m;