diff --git a/src/util/Structures.js b/src/util/Structures.js
index e80158a81..0c6ab35c7 100644
--- a/src/util/Structures.js
+++ b/src/util/Structures.js
@@ -1,5 +1,26 @@
 'use strict';
 
+/**
+ * An extendable structure:
+ * * **`GuildEmoji`**
+ * * **`DMChannel`**
+ * * **`TextChannel`**
+ * * **`VoiceChannel`**
+ * * **`CategoryChannel`**
+ * * **`NewsChannel`**
+ * * **`StoreChannel`**
+ * * **`GuildMember`**
+ * * **`Guild`**
+ * * **`Message`**
+ * * **`MessageReaction`**
+ * * **`Presence`**
+ * * **`ClientPresence`**
+ * * **`VoiceState`**
+ * * **`Role`**
+ * * **`User`**
+ * @typedef {string} ExtendableStructure
+ */
+
 /**
  * Allows for the extension of built-in Discord.js structures that are instantiated by {@link BaseManager Managers}.
  */
@@ -22,7 +43,7 @@ class Structures {
    * Extends a structure.
    * <warn> Make sure to extend all structures before instantiating your client.
    * Extending after doing so may not work as expected. </warn>
-   * @param {string} structure Name of the structure class to extend
+   * @param {ExtendableStructure} structure Name of the structure class to extend
    * @param {Function} extender Function that takes the base class to extend as its only parameter and returns the
    * extended class/prototype
    * @returns {Function} Extended class/prototype returned from the extender