diff --git a/ops/nixos/kusakabe/default.nix b/ops/nixos/kusakabe/default.nix
index 1aeb021242..dfe51e455e 100644
--- a/ops/nixos/kusakabe/default.nix
+++ b/ops/nixos/kusakabe/default.nix
@@ -98,7 +98,7 @@ in {
         # PostgreSQL
         5432
       ];
-      allowedTCPPorts = [ 80 443 ];
+      allowedTCPPorts = [ 80 443 6443 ];
     };
   };
   boot.kernel.sysctl."net.ipv4.ip_forward" = 1;