diff --git a/flake.nix b/flake.nix
index ca7fc93..f370375 100644
--- a/flake.nix
+++ b/flake.nix
@@ -194,7 +194,7 @@
               lib.mkIf cfg.enable {
                 assertions = [
                   {
-                    assertion = cfg.passwordFile == null && cfg.password == null;
+                    assertion = !(cfg.passwordFile == null && cfg.password == null);
                     message = "Must specifiy either passwordFile or password";
                   }
                 ];