diff --git a/lib/lists.nix b/lib/lists.nix
index bebb1d04..f0f0ea07 100644
--- a/lib/lists.nix
+++ b/lib/lists.nix
@@ -4,5 +4,6 @@
     let
       fullPath = name: "${toString dir}/${name}";
     in
-    map fullPath (lib.attrNames (builtins.readDir dir));
+    map fullPath (lib.attrNames (lib.optionalAttrs
+      (builtins.pathExists dir) (builtins.readDir dir)));
 }