diff --git a/flake.nix b/flake.nix
index a012827..8d1e0d0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,8 +5,10 @@
       url = "github:nix-community/home-manager";
       inputs.nixpkgs.follows = "nixpkgs";
     };
-    simple-nixos-mailserver.url =
-      "gitlab:simple-nixos-mailserver/nixos-mailserver";
+    simple-nixos-mailserver = {
+      url = "gitlab:simple-nixos-mailserver/nixos-mailserver";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     emacs-overlay = {
       url = "github:nix-community/emacs-overlay";
       inputs.nixpkgs.follows = "nixpkgs";