diff --git a/docs/nix/default.nix b/docs/nix/default.nix
index 0e16c705a..01dae322f 100644
--- a/docs/nix/default.nix
+++ b/docs/nix/default.nix
@@ -26,6 +26,7 @@ pkgs.stdenv.mkDerivation {
       mkdocs-material
       mkdocs-rss-plugin
       mkdocs-macros
+      filelock # FIXME: this should be already provided by mkdocs-rss-plugin
     ]);
   configurePhase = ''
     mkdir -p ./site/reference/cli