diff --git a/hosts/server/configuration.nix b/hosts/server/configuration.nix
index 2fd4f22..aecfa76 100755
--- a/hosts/server/configuration.nix
+++ b/hosts/server/configuration.nix
@@ -147,6 +147,9 @@
 
     # This might create errors
     proxy_cookie_path / "/; secure; HttpOnly; SameSite=strict";
+
+    # prevent invalid subdomains "invalid ssl certificate" error (blackhole)
+    virtualHosts."_".locations."/".return = "444";
   '';
   services.nginx.virtualHosts."reidlab.online" = {
     forceSSL = true;