diff --git a/hive.nix b/hive.nix
index 6d20a20..8aea0c8 100644
--- a/hive.nix
+++ b/hive.nix
@@ -81,6 +81,7 @@ in
 
 {
   meta = {
+    nixpkgs = import nixpkgs.nixos.unstable.path;
     nodeNixpkgs = mapSingleFuse nodePkgs nodes;
 
     specialArgs = {
diff --git a/machines/ap01/_configuration.nix b/machines/ap01/_configuration.nix
index e959da6..ebdd302 100644
--- a/machines/ap01/_configuration.nix
+++ b/machines/ap01/_configuration.nix
@@ -1,5 +1,6 @@
 {
   modulesPath,
+  sourcePkgs,
   ...
 }:
 {
@@ -36,4 +37,5 @@
   ];
 
   hostname = "ap01-prototype";
+  nixpkgs.source = sourcePkgs.path;
 }
diff --git a/scripts/cache-node.sh b/scripts/cache-node.sh
index 410403c..70c4f46 100755
--- a/scripts/cache-node.sh
+++ b/scripts/cache-node.sh
@@ -3,7 +3,7 @@ set -o nounset
 set -o pipefail
 shopt -s lastpipe
 
-system_type="$(colmena eval -E "{ nodes, ... }: nodes.${BUILD_NODE}.config.deployment.systemType")"
+system_type="$(colmena eval -E "{ nodes, ... }: nodes.${BUILD_NODE}.config.deployment.systemType" --show-trace)"
 # Get rid of surrounding quotes.
 system_type="${system_type%\"}"
 system_type="${system_type#\"}"