diff --git a/nixpkgs_review/nix/evalAttrs.nix b/nixpkgs_review/nix/evalAttrs.nix
index e22b12c0..e28e7afb 100644
--- a/nixpkgs_review/nix/evalAttrs.nix
+++ b/nixpkgs_review/nix/evalAttrs.nix
@@ -3,18 +3,35 @@
 with builtins;
 let
   pkgs = import <nixpkgs> { config = { checkMeta = true; allowUnfree = true; inherit allowAliases; }; };
-  lib = pkgs.lib;
+  inherit (pkgs) lib;
 
   attrs = fromJSON (readFile attr-json);
-  getProperties = name: let
-    attrPath = lib.splitString "." name;
-    pkg = lib.attrByPath attrPath null pkgs;
-    maybePath = builtins.tryEval "${pkg}";
-  in rec {
-    exists = lib.hasAttrByPath attrPath pkgs;
-    broken = !exists || !maybePath.success;
-    path = if !broken then maybePath.value else null;
-    drvPath = if !broken then pkg.drvPath else null;
-  };
+  getProperties = name:
+    let
+      attrPath = lib.splitString "." name;
+      pkg = lib.attrByPath attrPath null pkgs;
+      debugAttr = attr: lib.concatStringsSep "   " (lib.mapAttrsToList
+        (name: value: "${name}=${value}")
+        (lib.mapAttrs
+          (name: value:
+            if (isAttrs value && lib.hasAttr "outPath" value) then
+              value.outPath
+            else
+              "")
+          attr
+        )
+      );
+      maybePath =
+        if lib.strings.isCoercibleToString pkg then
+          tryEval "${pkg}"
+        else
+          throw "Tried building attr set with the following content: ${debugAttr pkg}";
+    in
+    rec {
+      exists = lib.hasAttrByPath attrPath pkgs;
+      broken = !exists || !maybePath.success;
+      path = if !broken then maybePath.value else null;
+      drvPath = if !broken then pkg.drvPath else null;
+    };
 in
-  pkgs.lib.genAttrs attrs getProperties
+pkgs.lib.genAttrs attrs getProperties