diff --git a/overlay.nix b/overlay.nix
index d526d5b..5b7e546 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -34,7 +34,7 @@ in
   };
 
   # force these onto upstream so we are not regularly rebuilding electron
-  prefetch-yarn-deps = prev.prefetch-yarn-deps.override {
+  prefetch-yarn-deps = (final.lib.trace "overriding: ${toString (builtins.attrNames prev.prefetch-yarn-deps)}" prev.prefetch-yarn-deps).override {
     nix = final.nixVersions.nix_2_18_upstream;
   };
   prefetch-npm-deps = prev.prefetch-npm-deps.override {