diff --git a/lib/options.nix b/lib/options.nix
index afae1769afdd..3a1c0e540d7c 100644
--- a/lib/options.nix
+++ b/lib/options.nix
@@ -242,6 +242,8 @@ rec {
           in if ss != {} then optionAttrSetToDocList' opt.loc ss else [];
         subOptionsVisible = docOption.visible && opt.visible or null != "shallow";
       in
+        # To find infinite recursion in NixOS option docs:
+        # builtins.trace opt.loc
         [ docOption ] ++ optionals subOptionsVisible subOptions) (collect isOption options);