diff --git a/source/item/item.ts b/source/item/item.ts
index e04b185..b4da283 100644
--- a/source/item/item.ts
+++ b/source/item/item.ts
@@ -31,6 +31,13 @@ export type SerializedItem = {
 /** The key prefix for {@link Item}s. */
 export type ItemKeyPrefix = "item-" | "history-";
 
+/**
+ * Returns the dedicated WebExtension storage area for a given
+ * {@link ItemKeyPrefix}.
+ *
+ * @param prefix The target {@link ItemKeyPrefix}.
+ * @returns The WebExtension storage area.
+ */
 export function storageForPrefix(
   prefix: ItemKeyPrefix,
 ): browser.Storage.StorageArea {