diff --git a/conf/nginx.conf b/conf/nginx.conf
index f07531d..eb2e105 100644
--- a/conf/nginx.conf
+++ b/conf/nginx.conf
@@ -4,7 +4,7 @@ set $allowed_origins "https://${sandbox_domain}";
 set $api_domain "__DOMAIN__";
 set $files_domain "__DOMAIN__";
 ssl_ecdh_curve secp384r1;
-more_set_headers "Strict-Transport-Security: 'max-age=31536000; includeSubDomains' always";
+more_set_headers "Strict-Transport-Security: max-age=31536000; includeSubDomains; always";
 more_set_headers "X-XSS-Protection: '1; mode=block'";
 more_set_headers "X-Content-Type-Options: nosniff";
 more_set_headers "Access-Control-Allow-Origin: '${allowed_origins}'";