diff --git a/lib/inventory/build-inventory/interface.nix b/lib/inventory/build-inventory/interface.nix
index 01c25c37b..b496bb962 100644
--- a/lib/inventory/build-inventory/interface.nix
+++ b/lib/inventory/build-inventory/interface.nix
@@ -343,7 +343,12 @@ in
         }
       );
       default = { };
-      apply = lib.warn "Inventory.instances and related features are still under development. Please use with care.";
+      apply =
+        v:
+        if v == { } then
+          v
+        else
+          lib.warn "Inventory.instances and related features are still under development. Please use with care." v;
     };
     services = lib.mkOption {
       description = ''