diff --git a/deployment/check/common/nixosTest.nix b/deployment/check/common/nixosTest.nix
index cb52ed9f..bc30edba 100644
--- a/deployment/check/common/nixosTest.nix
+++ b/deployment/check/common/nixosTest.nix
@@ -48,7 +48,8 @@ in
     extraTestScript = mkOption { };
 
     sourceFileset = mkOption {
-      ## REVIEW: Upstream to nixpkgs?
+      ## FIXME: grab `lib.types.fileset` from NixOS, once upstreaming PR
+      ## https://github.com/NixOS/nixpkgs/pull/428293 lands.
       type = types.mkOptionType {
         name = "fileset";
         description = "fileset";