diff --git a/modules/lix-bug-details-pls/default.nix b/modules/lix-bug-details-pls/default.nix
index eca78a5..4574516 100644
--- a/modules/lix-bug-details-pls/default.nix
+++ b/modules/lix-bug-details-pls/default.nix
@@ -12,7 +12,7 @@
   nixpkgs.overlays = [
     (final: prev: {
       lix = prev.lix.overrideAttrs (old: {
-        patches = old.patches ++ [
+        patches = (old.patches or [ ]) ++ [
           ./0001-wip-complain-about-failing-goals-at-warn-level.patch
         ];
       });