diff --git a/pack/overrides/kubejs/client_scripts/jei_hides.js b/pack/overrides/kubejs/client_scripts/jei_hides.js
index eb6db8d..637a36e 100644
--- a/pack/overrides/kubejs/client_scripts/jei_hides.js
+++ b/pack/overrides/kubejs/client_scripts/jei_hides.js
@@ -42,12 +42,17 @@ const COIN_ITEMS = [
     'numismatics:sun',
 ];
 
+// Some IDs may not exist (e.g. base 'waystones:sharestone' isn't
+// registered if only colored variants are). Swallow per-item failures
+// so one bad id doesn't break the whole pass.
+function hideQuietly(event, id) {
+    try { event.hide(id); } catch (e) {}
+}
+
 JEIEvents.hideItems(event => {
-    [...WAYSTONE_ITEMS, ...COIN_ITEMS].forEach(id => {
-        try { event.hide(id); } catch (e) {
-            // Some IDs may not exist (e.g. base 'waystones:sharestone' isn't
-            // registered if only colored variants are). Swallow per-item
-            // failures so one bad id doesn't break the whole pass.
-        }
+    // KubeJS uses Rhino, which doesn't support array-spread syntax
+    // (`[...a, ...b]`). Use .concat() for cross-engine safety.
+    WAYSTONE_ITEMS.concat(COIN_ITEMS).forEach(function(id) {
+        hideQuietly(event, id);
     });
 });
diff --git a/pack/pack.lock.json b/pack/pack.lock.json
index 156fb6e..fe54bab 100644
--- a/pack/pack.lock.json
+++ b/pack/pack.lock.json
@@ -1,7 +1,7 @@
 {
   "$schema": "Brass-and-Sigil pack.lock.json - generated, do not edit by hand unless you know what you are doing",
   "name": "Brass and Sigil",
-  "version": "0.21.0",
+  "version": "0.21.1",
   "minecraft": "1.21.1",
   "loader": {
     "type": "neoforge",