diff --git a/js/game.js b/js/game.js
index 8832d76..a1b2402 100644
--- a/js/game.js
+++ b/js/game.js
@@ -1013,14 +1013,17 @@ export class Level {
 
         let type = TILE_TYPES[name];
         if (type.is_key) {
-            actor.keyring ||= {};
-            actor.keyring[name] ||= 0;
-            actor.keyring[name] += 1;
+            if (! actor.keyring) {
+                actor.keyring = {};
+            }
+            actor.keyring[name] = (actor.keyring[name] ?? 0) + 1;
             this.pending_undo.push(() => actor.keyring[name] -= 1);
         }
         else {
             // tool, presumably
-            actor.toolbelt ||= [];
+            if (! actor.toolbelt) {
+                actor.toolbelt = [];
+            }
             actor.toolbelt.push(name);
             this.pending_undo.push(() => actor.toolbelt.pop());
         }