diff --git a/lib/inventory/build-inventory/interface.nix b/lib/inventory/build-inventory/interface.nix
index d505c2fc0..e77046a8b 100644
--- a/lib/inventory/build-inventory/interface.nix
+++ b/lib/inventory/build-inventory/interface.nix
@@ -62,6 +62,7 @@ let
       ```
 
     '';
+    apply = value: if lib.isString value then value else builtins.seq (builtins.toJSON value) value;
     default = [ ];
     type = types.listOf (
       types.oneOf [