diff --git a/src/client/theme-default/support/lru.ts b/src/client/theme-default/support/lru.ts
index fdf5bcd4..bad3f2b4 100644
--- a/src/client/theme-default/support/lru.ts
+++ b/src/client/theme-default/support/lru.ts
@@ -1,3 +1,5 @@
+// adapted from https://stackoverflow.com/a/46432113/11613622
+
 export class LRUCache<K, V> {
   private max: number
   private cache: Map<K, V>