diff --git a/nixos/modules/issuer.nix b/nixos/modules/issuer.nix
index 85c39c7271e9273b5e299980ebf7a46849bc9457..5cec1c4a9dc07f297abab049790dbf970388c91b 100644
--- a/nixos/modules/issuer.nix
+++ b/nixos/modules/issuer.nix
@@ -224,6 +224,12 @@ in {
           '';
           proxyPass = "http://127.0.0.1:${internalHttpPort}";
         };
+        locations."/" = {
+          # Return a 404 error for any paths not specified above.
+          extraConfig = ''
+            return 404;
+          '';
+        };
       };
     };