diff --git a/nixos/modules/system/activation/top-level.nix b/nixos/modules/system/activation/top-level.nix
index 026fd1791d33f..e68c267320d8f 100644
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -177,6 +177,7 @@ in
           };
 
           options.configuration = mkOption {
+            type = with types; oneOf [ attrs (functionTo attrs) path ];
             default = {};
             description = "Arbitrary NixOS configuration options.";
           };