diff --git a/flake.nix b/flake.nix
index 10720e1..f51717e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -72,7 +72,7 @@
                 };
 
                 secret_key_file = mkOption {
-                  type = types.string;
+                  type = types.str;
                   example = "/var/lib/skey";
                   description = "The Secrert key for Phoenix";
                 };